When reprobing an MST topology during resume, we have to account for the
fact that while we were suspended it's possible that mstbs may have been
removed from any ports in the topology. Since iterating downwards in the
topology requires that we hold &mgr->lock, destroying MSTBs from this
context would result in attempting to lock &mgr->lock a second time and
deadlocking.

So, fix this by first moving destruction of MSTBs into
destroy_connector_work, then rename destroy_connector_work and friends
to reflect that they now destroy both ports and mstbs.

Note that even though this means that MSTBs will still be accessible for
a short period of time between their removal from the topology and
delayed destruction, we are still protected against referencing a MSTB
with a refcount of 0 since we use kref_get_unless_zero() in most places.

Changes since v1:
* s/destroy_connector_list/destroy_port_list/
  s/connector_destroy_lock/delayed_destroy_lock/
  s/connector_destroy_work/delayed_destroy_work/
  s/drm_dp_finish_destroy_branch_device/drm_dp_delayed_destroy_mstb/
  s/drm_dp_finish_destroy_port/drm_dp_delayed_destroy_port/
  - danvet
* Use two loops in drm_dp_delayed_destroy_work() - danvet
* Better explain why we need to do this - danvet
* Use cancel_work_sync() instead of flush_work() - flush_work() doesn't
  account for work requeing

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: NSean Paul <sean@poorly.run>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191022023641.8026-2-lyude@redhat.com

Add helper to check if a drm debug category is enabled. Convert drm core
to use it. No functional changes.

v2: Move unlikely() to drm_debug_enabled() (Eric)

v3: Keep unlikely() when combined with other conditions (Eric)

Cc: Eric Engestrom <eric@engestrom.ch>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NEric Engestrom <eric@engestrom.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191001140614.26909-1-jani.nikula@intel.com

Get rid of the drm_fixp_from_fraction() usage and just do the
straightforward calculation directly.

Cc: Lyude Paul <lyude@redhat.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925141442.23236-3-ville.syrjala@linux.intel.comReviewed-by: NLyude Paul <lyude@redhat.com>

Make drm_dp_get_vc_payload() tolerate arbitrary DP_LINK_BW_*
values, just like drm_dp_bw_code_to_link_rate() does since commit
57a1b089 ("drm: Make the bw/link rate calculations more forgiving").

Cc: Lyude Paul <lyude@redhat.com>
Cc: Sean Paul <seanpaul@chromium.org>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925141442.23236-2-ville.syrjala@linux.intel.comReviewed-by: NLyude Paul <lyude@redhat.com>

Replace the nested ifs with a single if and a logical AND.

Cc: Lyude Paul <lyude@redhat.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925141442.23236-1-ville.syrjala@linux.intel.comReviewed-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NLyude Paul <lyude@redhat.com>

It looks like one of the topology manager mutexes may have been renamed
during a rebase, but the destruction function wasn't updated with the
new name:

   error: ‘struct drm_dp_mst_topology_mgr’ has no member named
   ‘delayed_destroy_lock’

Fixes: 50094b5d ("drm/dp_mst: Destroy topology_mgr mutexes")
Cc: Lyude Paul <lyude@redhat.com>
Cc: Sean Paul <sean@poorly.run>
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Reviewed-by: NLyude Paul <lyude@redhat.com>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925224617.24027-1-matthew.d.roper@intel.com

The names for these functions are rather confusing. drm_dp_add_port()
sounds like a function that would simply create a port and add it to a
topology, and do nothing more. Similarly, drm_dp_update_port() would be
assumed to be the function that should be used to update port
information after initial creation.

While those assumptions are currently correct in how these functions are
used, a quick glance at drm_dp_add_port() reveals that drm_dp_add_port()
can also update the information on a port, and seems explicitly designed
to do so. This can be explained pretty simply by the fact that there's
more situations that would involve updating the port information based
on a link address response as opposed to a connection status
notification than the driver's initial topology probe. Case in point:
reprobing link addresses after suspend/resume.

Since we're about to start using drm_dp_add_port() differently for
suspend/resume reprobing, let's rename both functions to clarify what
they actually do.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NSean Paul <sean@poorly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-18-lyude@redhat.com

Turns out we've been forgetting for a while now to actually destroy any
of the mutexes that we create in drm_dp_mst_topology_mgr. So, let's do
that.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NSean Paul <sean@poorly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-15-lyude@redhat.com

Declare local pointer to the drm_dp_link_address_ack_reply struct
instead of constantly dereferencing it through the union in
txmsg->reply. Then, invert the order of conditionals so we don't have to
do the bulk of the work inside them, and can wrap lines even less. Then
finally, rearrange variable declarations a bit.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-16-lyude@redhat.com

* Remove the big ugly have_eomt conditional
* Store &mgr->down_rep_recv.initial_hdr in a var to make line wrapping
  easier
* Remove duplicate memset() calls
* Actually wrap lines

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-14-lyude@redhat.com

There's a couple of changes here, so to summarize:

* Remove the big ugly mgr->up_req_recv.have_eomt conditional to save on
  indenting
* Store &mgr->up_req_recv.initial_hdr in a variable so we don't keep
  going over 80 character long lines
* De-duplicate code for calling drm_dp_send_up_ack_reply() and getting
  the MSTB via it's GUID
* Remove all of the duplicate calls to memset() and just use a goto
  instead
* Actually do line wrapping
* Remove the unnecessary if (mstb) check before calling
  drm_dp_mst_topology_put_mstb() - we are guaranteed to always have
  mstb != NULL at that point in the function

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-13-lyude@redhat.com

And it's helper, we'll be using this in just a moment.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-12-lyude@redhat.com

Which reduces indentation and makes this function more legible.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-11-lyude@redhat.com

Use more pointers so we don't have to write out
txmsg->reply.u.path_resources each time. Also, fix line wrapping +
rearrange local variables.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-10-lyude@redhat.com

Unfortunately the DP MST helpers do not have much in the way of
debugging utilities. So, let's add some!

This adds basic debugging output for down sideband requests that we send
from the driver, so that we can actually discern what's happening when
sideband requests timeout.

Since there wasn't really a good way of testing that any of this worked,
I ended up writing simple selftests that lightly test sideband message
encoding and decoding as well. Enjoy!

Changes since v1:
* Clean up DO_TEST() and sideband_msg_req_encode_decode() - danvet
* Get rid of pr_fmt(), just define a prefix string instead and use
  drm_printf()
* Check highest bit of VCPI in drm_dp_decode_sideband_req() - danvet
* Make the switch case order between drm_dp_decode_sideband_req() and
  drm_dp_encode_sideband_req() the same - danvet
* Only check DRM_UT_DP - danvet
* Clean up sideband_msg_req_equal() from selftests a bit, and add
  comments explaining why we can't just use memcmp - danvet

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-8-lyude@redhat.com

Noticed this while working on adding a drm_dp_decode_sideband_req().
DP_POWER_DOWN_PHY/DP_POWER_UP_PHY both use the same struct as
DP_ENUM_PATH_RESOURCES, so we can just combine their cases.

Changes since v2:
* Fix commit message
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDave Airlie <airlied@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903215702.16984-1-lyude@redhat.com

Yes, apparently we've been testing this for every single driver load for
quite a long time now. At least that means our PBN calculation is solid!

Anyway, introduce self tests for MST and move this into there.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-5-lyude@redhat.com

This seems to be some leftover detritus from before the port/mstb kref
cleanup and doesn't do anything anymore, so get rid of it.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-3-lyude@redhat.com

Makes things easier to read.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Signed-off-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-2-lyude@redhat.com

Fixes the following warnings:

../drivers/gpu/drm/drm_dp_mst_topology.c:1593: warning: Excess function parameter 'drm_connector' description in 'drm_dp_mst_connector_late_register'
../drivers/gpu/drm/drm_dp_mst_topology.c:1613: warning: Excess function parameter 'drm_connector' description in 'drm_dp_mst_connector_early_unregister'
../drivers/gpu/drm/drm_dp_mst_topology.c:1594: warning: Function parameter or member 'connector' not described in 'drm_dp_mst_connector_late_register'
../drivers/gpu/drm/drm_dp_mst_topology.c:1614: warning: Function parameter or member 'connector' not described in 'drm_dp_mst_connector_early_unregister'

Fixes: 562836a2 ("drm/dp_mst: Enable registration of AUX devices for MST ports")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: NLyude Paul <lyude@redhat.com>
Signed-off-by: NSean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190726142057.224121-1-sean@poorly.run

All available downstream ports - physical and logical - are exposed for
each MST device. They are listed in /dev/, following the same naming
scheme as SST devices by appending an incremental ID.

Although all downstream ports are exposed, only some will work as
expected. Consider the following topology:

               +---------+
               |  ASIC   |
               +---------+
              Conn-0|
                    |
               +----v----+
          +----| MST HUB |----+
          |    +---------+    |
          |                   |
          |Port-1       Port-2|
    +-----v-----+       +-----v-----+
    |  MST      |       |  SST      |
    |  Display  |       |  Display  |
    +-----------+       +-----------+
          |Port-1
          x

 MST Path  | MST Device
 ----------+----------------------------------
 sst:0     | MST Hub
 mst:0-1   | MST Display
 mst:0-1-1 | MST Display's disconnected DP out
 mst:0-1-8 | MST Display's internal sink
 mst:0-2   | SST Display

On certain MST displays, the upstream physical port will ACK DPCD reads.
However, reads on the local logical port to the internal sink will
*NAK*. i.e. reading mst:0-1 ACKs, but mst:0-1-8 NAKs.

There may also be duplicates. Some displays will return the same GUID
when reading DPCD from both mst:0-1 and mst:0-1-8.

There are some device-dependent behavior as well. The MST hub used
during testing will actually *ACK* read requests on a disconnected
physical port, whereas the MST displays will NAK.

In light of these discrepancies, it's simpler to expose all downstream
ports - both physical and logical - and let the user decide what to use.

v3 changes:
* Change WARN_ON_ONCE -> DRM_ERROR on dpcd read errors
* Docstring and cosmetic fixes

v2 changes:

Moved remote aux device (un)registration to new mst connector late
register and early unregister helpers. Drivers should call these from
their own mst connector function hooks.

This is to solve an issue during driver unload, where mst connector
devices are unregistered before the remote aux devices are. In a setup
where aux devices are created as children of connector devices, the aux
device would be removed too early, and uncleanly. Doing so in
early_unregister solves this issue, as that is called before connector
unregistration.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NLeo Li <sunpeng.li@amd.com>
Reviewed-by: NLyude Paul <lyude@redhat.com>
Signed-off-by: NHarry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190723232808.28128-3-sunpeng.li@amd.com

Fix the breakage resulting in the stacktrace below, due to tx queue
being full when trying to send an up-reply. txmsg->seqno is -1 in this
case leading to a corruption of the mstb object by

	txmsg->dst->tx_slots[txmsg->seqno] = NULL;

in process_single_up_tx_qlock().

[  +0,005162] [drm:process_single_tx_qlock [drm_kms_helper]] set_hdr_from_dst_qlock: failed to find slot
[  +0,000015] [drm:drm_dp_send_up_ack_reply.constprop.19 [drm_kms_helper]] failed to send msg in q -11
[  +0,000939] BUG: kernel NULL pointer dereference, address: 00000000000005a0
[  +0,006982] #PF: supervisor write access in kernel mode
[  +0,005223] #PF: error_code(0x0002) - not-present page
[  +0,005135] PGD 0 P4D 0
[  +0,002581] Oops: 0002 [#1] PREEMPT SMP NOPTI
[  +0,004359] CPU: 1 PID: 1200 Comm: kworker/u16:3 Tainted: G     U            5.2.0-rc1+ #410
[  +0,008433] Hardware name: Intel Corporation Ice Lake Client Platform/IceLake U DDR4 SODIMM PD RVP, BIOS ICLSFWR1.R00.3175.A00.1904261428 04/26/2019
[  +0,013323] Workqueue: i915-dp i915_digport_work_func [i915]
[  +0,005676] RIP: 0010:queue_work_on+0x19/0x70
[  +0,004372] Code: ff ff ff 0f 1f 40 00 66 2e 0f 1f 84 00 00 00 00 00 41 56 49 89 f6 41 55 41 89 fd 41 54 55 53 48 89 d3 9c 5d fa e8 e7 81 0c 00 <f0> 48 0f ba 2b 00 73 31 45 31 e4 f7 c5 00 02 00 00 74 13 e8 cf 7f
[  +0,018750] RSP: 0018:ffffc900007dfc50 EFLAGS: 00010006
[  +0,005222] RAX: 0000000000000046 RBX: 00000000000005a0 RCX: 0000000000000001
[  +0,007133] RDX: 000000000001b608 RSI: 0000000000000000 RDI: ffffffff82121972
[  +0,007129] RBP: 0000000000000202 R08: 0000000000000000 R09: 0000000000000001
[  +0,007129] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88847bfa5096
[  +0,007131] R13: 0000000000000010 R14: ffff88849c08f3f8 R15: 0000000000000000
[  +0,007128] FS:  0000000000000000(0000) GS:ffff88849dc80000(0000) knlGS:0000000000000000
[  +0,008083] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  +0,005749] CR2: 00000000000005a0 CR3: 0000000005210006 CR4: 0000000000760ee0
[  +0,007128] PKRU: 55555554
[  +0,002722] Call Trace:
[  +0,002458]  drm_dp_mst_handle_up_req+0x517/0x540 [drm_kms_helper]
[  +0,006197]  ? drm_dp_mst_hpd_irq+0x5b/0x9c0 [drm_kms_helper]
[  +0,005764]  drm_dp_mst_hpd_irq+0x5b/0x9c0 [drm_kms_helper]
[  +0,005623]  ? intel_dp_hpd_pulse+0x205/0x370 [i915]
[  +0,005018]  intel_dp_hpd_pulse+0x205/0x370 [i915]
[  +0,004836]  i915_digport_work_func+0xbb/0x140 [i915]
[  +0,005108]  process_one_work+0x245/0x610
[  +0,004027]  worker_thread+0x37/0x380
[  +0,003684]  ? process_one_work+0x610/0x610
[  +0,004184]  kthread+0x119/0x130
[  +0,003240]  ? kthread_park+0x80/0x80
[  +0,003668]  ret_from_fork+0x24/0x50

Cc: Lyude Paul <lyude@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NLyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190523212433.9058-1-imre.deak@intel.com

Continue to get rid of drmP.h. Add minimal includes to build. Sort
includes while at it.
Reviewed-by: NNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190506095248.20874-1-jani.nikula@intel.com

Current driver sets the tile property only for DP MST connectors.
However there are some tiled displays where each SST connector
carries a single tile. So we need to attach this property object
for every connector and set it for every connector (DP SST and MST).
Plus since the tile information is obtained as a result of EDID
parsing, the best place to update tile property is where we update
edid property.
Also now we dont need to explicitly set this now for MST connectors.

This has been tested with xrandr --props and modetest and verified
that TILE property is exposed correctly.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NManasi Navare <manasi.d.navare@intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190313021722.10068-1-manasi.d.navare@intel.com

Looks like when making the final revision of:

commit 022debad ("drm/atomic: Add drm_atomic_state->duplicated")

I forgot to remove some of the comments that I had added to
drm_dp_atomic_find_vcpi_slots() and drm_dp_atomic_release_vcpi_slots()
that were no longer valid due to us having removed the state->duplicated
checks from each function. This also introduced an error while building
the docs with sphinx:

./drivers/gpu/drm/drm_dp_mst_topology.c:3100: WARNING: Inline literal
start-string without end-string.

So, fix that by just removing the kerneldoc comments.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Fixes: 022debad ("drm/atomic: Add drm_atomic_state->duplicated")
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-5-lyude@redhat.com

Since

commit 39b50c60 ("drm/atomic_helper: Stop modesets on unregistered
connectors harder")

We've been failing atomic checks if they try to enable new displays on
unregistered connectors. This is fine except for the one situation that
breaks atomic assumptions: suspend/resume. If a connector is
unregistered before we attempt to restore the atomic state, something we
end up failing the atomic check that happens when trying to restore the
state during resume.

Normally this would be OK: we try our best to make sure that the atomic
state pre-suspend can be restored post-suspend, but failures at that
point usually don't cause problems. That is of course, until we
introduced the new atomic MST VCPI helpers:

[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] [CRTC:65:pipe B] active changed
[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] Updating routing for [CONNECTOR:123:DP-5]
[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] Disabling [CONNECTOR:123:DP-5]
[drm:drm_atomic_get_private_obj_state [drm]] Added new private object 0000000025844636 state 000000009fd2899a to 000000003a13d7b8
WARNING: CPU: 6 PID: 1070 at drivers/gpu/drm/drm_dp_mst_topology.c:3153 drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
Modules linked in: fuse vfat fat snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic joydev iTCO_wdt i915(O) wmi_bmof intel_rapl btusb btrtl x86_pkg_temp_thermal btbcm btintel coretemp i2c_algo_bit drm_kms_helper(O) crc32_pclmul snd_hda_intel syscopyarea sysfillrect snd_hda_codec sysimgblt snd_hda_core bluetooth fb_sys_fops snd_pcm pcspkr drm(O) psmouse snd_timer mei_me ecdh_generic i2c_i801 mei i2c_core ucsi_acpi typec_ucsi typec wmi thinkpad_acpi ledtrig_audio snd soundcore tpm_tis rfkill tpm_tis_core video tpm acpi_pad pcc_cpufreq uas usb_storage crc32c_intel nvme serio_raw xhci_pci nvme_core xhci_hcd
CPU: 6 PID: 1070 Comm: gnome-shell Tainted: G        W  O      5.0.0-rc2Lyude-Test+ #1
Hardware name: LENOVO 20L8S2N800/20L8S2N800, BIOS N22ET35W (1.12 ) 04/09/2018
RIP: 0010:drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
Code: 00 4c 39 6d f0 74 49 48 8d 7b 10 48 89 f9 48 c1 e9 03 42 80 3c 21 00 0f 85 d2 00 00 00 48 8b 6b 10 48 8d 5d f0 49 39 ee 75 c5 <0f> 0b 48 c7 c7 c0 78 b3 a0 48 89 c2 4c 89 ee e8 03 6c aa ff b8 ea
RSP: 0018:ffff88841235f268 EFLAGS: 00010246
RAX: ffff88841bf12ab0 RBX: ffff88841bf12aa8 RCX: 1ffff110837e2557
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffed108246bde0
RBP: ffff88841bf12ab8 R08: ffffed1083db3c93 R09: ffffed1083db3c92
R10: ffffed1083db3c92 R11: ffff88841ed9e497 R12: ffff888419555d80
R13: ffff8883bc499100 R14: ffff88841bf12ab8 R15: 0000000000000000
FS:  00007f16fbd4cd00(0000) GS:ffff88841ed80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1687c9f000 CR3: 00000003ba3cc003 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 drm_atomic_helper_check_modeset+0xf21/0x2f50 [drm_kms_helper]
 ? drm_atomic_helper_commit_modeset_enables+0xa90/0xa90 [drm_kms_helper]
 ? __printk_safe_exit+0x10/0x10
 ? save_stack+0x8c/0xb0
 ? vprintk_func+0x96/0x1bf
 ? __printk_safe_exit+0x10/0x10
 intel_atomic_check+0x234/0x4750 [i915]
 ? printk+0x9f/0xc5
 ? kmsg_dump_rewind_nolock+0xd9/0xd9
 ? _raw_spin_lock_irqsave+0xa4/0x140
 ? drm_atomic_check_only+0xb1/0x28b0 [drm]
 ? drm_dbg+0x186/0x1b0 [drm]
 ? drm_dev_dbg+0x200/0x200 [drm]
 ? intel_link_compute_m_n+0xb0/0xb0 [i915]
 ? drm_mode_put_tile_group+0x20/0x20 [drm]
 ? skl_plane_format_mod_supported+0x17f/0x1b0 [i915]
 ? drm_plane_check_pixel_format+0x14a/0x310 [drm]
 drm_atomic_check_only+0x13c4/0x28b0 [drm]
 ? drm_state_info+0x220/0x220 [drm]
 ? drm_atomic_helper_disable_plane+0x1d0/0x1d0 [drm_kms_helper]
 ? pick_single_encoder_for_connector+0xe0/0xe0 [drm_kms_helper]
 ? kasan_unpoison_shadow+0x35/0x40
 drm_atomic_commit+0x3b/0x100 [drm]
 drm_atomic_helper_set_config+0xd5/0x100 [drm_kms_helper]
 drm_mode_setcrtc+0x636/0x1660 [drm]
 ? vprintk_func+0x96/0x1bf
 ? drm_dev_dbg+0x200/0x200 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? printk+0x9f/0xc5
 ? mutex_unlock+0x1d/0x40
 ? drm_mode_addfb2+0x2e9/0x3a0 [drm]
 ? rcu_sync_dtor+0x2e0/0x2e0
 ? drm_dbg+0x186/0x1b0 [drm]
 ? set_page_dirty+0x271/0x4d0
 drm_ioctl_kernel+0x203/0x290 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? drm_setversion+0x7f0/0x7f0 [drm]
 ? __switch_to_asm+0x34/0x70
 ? __switch_to_asm+0x34/0x70
 drm_ioctl+0x445/0x950 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? drm_getunique+0x220/0x220 [drm]
 ? expand_files.part.10+0x920/0x920
 do_vfs_ioctl+0x1a1/0x13d0
 ? ioctl_preallocate+0x2b0/0x2b0
 ? __fget_light+0x2d6/0x390
 ? schedule+0xd7/0x2e0
 ? fget_raw+0x10/0x10
 ? apic_timer_interrupt+0xa/0x20
 ? apic_timer_interrupt+0xa/0x20
 ? rcu_cleanup_dead_rnp+0x2c0/0x2c0
 ksys_ioctl+0x60/0x90
 __x64_sys_ioctl+0x6f/0xb0
 do_syscall_64+0x136/0x440
 ? syscall_return_slowpath+0x2d0/0x2d0
 ? do_page_fault+0x89/0x330
 ? __do_page_fault+0x9c0/0x9c0
 ? prepare_exit_to_usermode+0x188/0x200
 ? perf_trace_sys_enter+0x1090/0x1090
 ? __x64_sys_sigaltstack+0x280/0x280
 ? __put_user_4+0x1c/0x30
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f16ff89a09b
Code: 0f 1e fa 48 8b 05 ed bd 0c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d bd bd 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007fff001232b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fff001232f0 RCX: 00007f16ff89a09b
RDX: 00007fff001232f0 RSI: 00000000c06864a2 RDI: 000000000000000b
RBP: 00007fff001232f0 R08: 0000000000000000 R09: 000055a79d484460
R10: 000055a79d44e770 R11: 0000000000000246 R12: 00000000c06864a2
R13: 000000000000000b R14: 0000000000000000 R15: 000055a79d44e770
WARNING: CPU: 6 PID: 1070 at drivers/gpu/drm/drm_dp_mst_topology.c:3153 drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
---[ end trace d536c05c13c83be2 ]---
[drm:drm_dp_atomic_release_vcpi_slots [drm_kms_helper]] *ERROR* no VCPI for [MST PORT:00000000f9e2b143] found in mst state 000000009fd2899a

This appears to be happening because we destroy the VCPI allocations
when disabling all connected displays while suspending, and those VCPI
allocations don't get restored on resume due to failing to restore the
atomic state.

So, fix this by introducing the suspending option to
drm_atomic_helper_duplicate_state() and use that to indicate in the
atomic state that it's being used for suspending or resuming the system,
and thus needs to be fixed up by the driver. We can then use the new
state->duplicated hook to tell update_connector_routing() in
drm_atomic_check_modeset() to allow for modesets on unregistered
connectors, which allows us to restore atomic states that contain MST
topologies that were removed after the state was duplicated and thus:
mostly fixing suspend and resume. This just leaves some issues that were
introduced with nouveau, that will be addressed next.

Changes since v3:
* Remove ->duplicated hunks that I left in the VCPI helpers by accident.
  These don't need to be here, that was the supposed to be the purpose
  of the last revision
Changes since v2:
* Remove the changes in this patch to the VCPI helpers, they aren't
  needed anymore
Changes since v1:
* Rename suspend_or_resume to duplicated
Signed-off-by: NLyude Paul <lyude@redhat.com>
Fixes: eceae147 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-4-lyude@redhat.com

Since we now have an easy way of refcounting drm_dp_mst_port structs and
safely accessing their contents, there isn't any good reason to keep
validating ports here. It doesn't prevent us from performing modesets on
branch devices that have been removed either, and we already disallow
enabling new displays on unregistered connectors in
update_connector_routing() in drm_atomic_check_modeset(). All it does is
cause us to have to make weird special exceptions in our atomic
modesetting code. So, get rid of it entirely.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Fixes: eceae147 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-3-lyude@redhat.com

In drm_dp_mst_deallocate_vcpi(), we currently unconditionally call
drm_dp_mst_put_port_malloc() on the port that's passed to us, even if we
never successfully allocated VCPI to it. This is contrary to what we do
in drm_dp_mst_allocate_vcpi(), where we only call
drm_dp_mst_get_port_malloc() on the passed port if we successfully
allocated VCPI to it.

As a result, if drm_dp_mst_allocate_vcpi() fails during a modeset and
another successive modeset calls drm_dp_mst_deallocate_vcpi() we will
end up dropping someone else's malloc reference to the port. Example:

[  962.309260] ==================================================================
[  962.309290] BUG: KASAN: use-after-free in drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309296] Read of size 4 at addr ffff888416c30004 by task kworker/0:1H/500

[  962.309308] CPU: 0 PID: 500 Comm: kworker/0:1H Tainted: G        W  O      5.0.0-rc2Lyude-Test+ #1
[  962.309313] Hardware name: LENOVO 20L8S2N800/20L8S2N800, BIOS N22ET35W (1.12 ) 04/09/2018
[  962.309428] Workqueue: events_highpri intel_atomic_cleanup_work [i915]
[  962.309434] Call Trace:
[  962.309452]  dump_stack+0xad/0x150
[  962.309462]  ? dump_stack_print_info.cold.0+0x1b/0x1b
[  962.309472]  ? kmsg_dump_rewind_nolock+0xd9/0xd9
[  962.309504]  ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309515]  print_address_description+0x6c/0x23c
[  962.309542]  ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309568]  ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309577]  kasan_report.cold.3+0x1a/0x32
[  962.309605]  ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309631]  drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper]
[  962.309658]  ? drm_dp_mst_put_mstb_malloc+0x180/0x180 [drm_kms_helper]
[  962.309687]  drm_dp_mst_destroy_state+0xcd/0x120 [drm_kms_helper]
[  962.309745]  drm_atomic_state_default_clear+0x6ee/0xcc0 [drm]
[  962.309864]  intel_atomic_state_clear+0xe/0x80 [i915]
[  962.309928]  __drm_atomic_state_free+0x35/0xd0 [drm]
[  962.310044]  intel_atomic_cleanup_work+0x56/0x70 [i915]
[  962.310057]  process_one_work+0x884/0x1400
[  962.310067]  ? drain_workqueue+0x5a0/0x5a0
[  962.310075]  ? __schedule+0x87f/0x1e80
[  962.310086]  ? __sched_text_start+0x8/0x8
[  962.310095]  ? run_rebalance_domains+0x400/0x400
[  962.310110]  ? deref_stack_reg+0xb4/0x120
[  962.310117]  ? __read_once_size_nocheck.constprop.7+0x10/0x10
[  962.310124]  ? worker_enter_idle+0x47f/0x6a0
[  962.310134]  ? schedule+0xd7/0x2e0
[  962.310141]  ? __schedule+0x1e80/0x1e80
[  962.310148]  ? _raw_spin_lock_irq+0x9f/0x130
[  962.310155]  ? _raw_write_unlock_irqrestore+0x110/0x110
[  962.310164]  worker_thread+0x196/0x11e0
[  962.310175]  ? set_load_weight+0x2e0/0x2e0
[  962.310181]  ? __switch_to_asm+0x34/0x70
[  962.310187]  ? __switch_to_asm+0x40/0x70
[  962.310194]  ? process_one_work+0x1400/0x1400
[  962.310199]  ? __switch_to_asm+0x40/0x70
[  962.310205]  ? __switch_to_asm+0x34/0x70
[  962.310211]  ? __switch_to_asm+0x34/0x70
[  962.310216]  ? __switch_to_asm+0x40/0x70
[  962.310221]  ? __switch_to_asm+0x34/0x70
[  962.310226]  ? __switch_to_asm+0x40/0x70
[  962.310231]  ? __switch_to_asm+0x34/0x70
[  962.310236]  ? __switch_to_asm+0x40/0x70
[  962.310242]  ? syscall_return_via_sysret+0xf/0x7f
[  962.310248]  ? __switch_to_asm+0x34/0x70
[  962.310253]  ? __switch_to_asm+0x40/0x70
[  962.310258]  ? __switch_to_asm+0x34/0x70
[  962.310263]  ? __switch_to_asm+0x40/0x70
[  962.310268]  ? __switch_to_asm+0x34/0x70
[  962.310273]  ? __switch_to_asm+0x40/0x70
[  962.310281]  ? __schedule+0x87f/0x1e80
[  962.310292]  ? __sched_text_start+0x8/0x8
[  962.310300]  ? save_stack+0x8c/0xb0
[  962.310308]  ? __kasan_kmalloc.constprop.6+0xc6/0xd0
[  962.310313]  ? kthread+0x98/0x3a0
[  962.310318]  ? ret_from_fork+0x35/0x40
[  962.310334]  ? __wake_up_common+0x178/0x6f0
[  962.310343]  ? _raw_spin_lock_irqsave+0xa4/0x140
[  962.310349]  ? __lock_text_start+0x8/0x8
[  962.310355]  ? _raw_write_lock_irqsave+0x70/0x130
[  962.310360]  ? __lock_text_start+0x8/0x8
[  962.310371]  ? process_one_work+0x1400/0x1400
[  962.310376]  kthread+0x2e2/0x3a0
[  962.310383]  ? kthread_create_on_node+0xc0/0xc0
[  962.310389]  ret_from_fork+0x35/0x40

[  962.310401] Allocated by task 1462:
[  962.310410]  __kasan_kmalloc.constprop.6+0xc6/0xd0
[  962.310437]  drm_dp_add_port+0xd60/0x1960 [drm_kms_helper]
[  962.310464]  drm_dp_send_link_address+0x4b0/0x770 [drm_kms_helper]
[  962.310491]  drm_dp_check_and_send_link_address+0x197/0x1f0 [drm_kms_helper]
[  962.310515]  drm_dp_mst_link_probe_work+0x2b6/0x330 [drm_kms_helper]
[  962.310522]  process_one_work+0x884/0x1400
[  962.310529]  worker_thread+0x196/0x11e0
[  962.310533]  kthread+0x2e2/0x3a0
[  962.310538]  ret_from_fork+0x35/0x40

[  962.310543] Freed by task 500:
[  962.310550]  __kasan_slab_free+0x133/0x180
[  962.310555]  kfree+0x92/0x1a0
[  962.310581]  drm_dp_mst_put_port_malloc+0x14d/0x180 [drm_kms_helper]
[  962.310693]  intel_connector_destroy+0xb2/0xe0 [i915]
[  962.310747]  drm_mode_object_put.part.0+0x12b/0x1a0 [drm]
[  962.310802]  drm_atomic_state_default_clear+0x1f2/0xcc0 [drm]
[  962.310916]  intel_atomic_state_clear+0xe/0x80 [i915]
[  962.310972]  __drm_atomic_state_free+0x35/0xd0 [drm]
[  962.311083]  intel_atomic_cleanup_work+0x56/0x70 [i915]
[  962.311092]  process_one_work+0x884/0x1400
[  962.311098]  worker_thread+0x196/0x11e0
[  962.311103]  kthread+0x2e2/0x3a0
[  962.311108]  ret_from_fork+0x35/0x40

[  962.311116] The buggy address belongs to the object at ffff888416c30000
                which belongs to the cache kmalloc-2k of size 2048
[  962.311122] The buggy address is located 4 bytes inside of
                2048-byte region [ffff888416c30000, ffff888416c30800)
[  962.311124] The buggy address belongs to the page:
[  962.311132] page:ffffea00105b0c00 count:1 mapcount:0 mapping:ffff88841d003040 index:0x0 compound_mapcount: 0
[  962.311142] flags: 0x8000000000010200(slab|head)
[  962.311152] raw: 8000000000010200 dead000000000100 dead000000000200 ffff88841d003040
[  962.311159] raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
[  962.311162] page dumped because: kasan: bad access detected

So, bail early if drm_dp_mst_deallocate_vcpi() is called on a port with
no VCPI allocation. Additionally, clean up the surrounding kerneldoc
while we're at it since the port is assumed to be kept around because
the DRM driver is expected to hold a malloc reference to it, not just
us.

Changes since v1:
* Doc changes - danvet
Signed-off-by: NLyude Paul <lyude@redhat.com>
Fixes: eceae147 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202002023.29665-2-lyude@redhat.com

Most of these are just cases where code comments used contractions
(it's, who's) where they actually mean to use a possessive pronoun (its,
whose) or vice-versa.
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190202012326.20096-1-matthew.d.roper@intel.com

Decode the NAK reply fields to make it easier to parse the logs.

v2: s/STR/DP_STR/ to avoid conflict with some header stuff (0day)
    Use drm_dp_mst_req_type_str() more (DK)
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190122200301.18633-2-ville.syrjala@linux.intel.com

Make the code a bit easier to read by providing symbolic names
for the reply_type (ACK vs. NAK). Also clean up some brace stuff
while at it.

v2: s/DP_REPLY/DP_SIDEBAND_REPLY/ (DK)
    Fix some checkpatch issues
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190122200301.18633-1-ville.syrjala@linux.intel.com

Having the probe helper stuff (which pretty much everyone needs) in
the drm_crtc_helper.h file (which atomic drivers should never need) is
confusing. Split them out.

To make sure I actually achieved the goal here I went through all
drivers. And indeed, all atomic drivers are now free of
drm_crtc_helper.h includes.

v2: Make it compile. There was so much compile fail on arm drivers
that I figured I'll better not include any of the acks on v1.

v3: Massive rebase because i915 has lost a lot of drmP.h includes, but
not all: Through drm_crtc_helper.h > drm_modeset_helper.h -> drmP.h
there was still one, which this patch largely removes. Which means
rolling out lots more includes all over.

This will also conflict with ongoing drmP.h cleanup by others I
expect.

v3: Rebase on top of atomic bochs.

v4: Review from Laurent for bridge/rcar/omap/shmob/core bits:
- (re)move some of the added includes, use the better include files in
  other places (all suggested from Laurent adopted unchanged).
- sort alphabetically

v5: Actually try to sort them, and while at it, sort all the ones I
touch.

v6: Rebase onto i915 changes.

v7: Rebase once more.
Acked-by: NHarry Wentland <harry.wentland@amd.com>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Acked-by: NJani Nikula <jani.nikula@intel.com>
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>
Acked-by: NOleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: NCK Hu <ck.hu@mediatek.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: NLiviu Dudau <liviu.dudau@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: virtualization@lists.linux-foundation.org
Cc: etnaviv@lists.freedesktop.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-mediatek@lists.infradead.org
Cc: linux-amlogic@lists.infradead.org
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: spice-devel@lists.freedesktop.org
Cc: amd-gfx@lists.freedesktop.org
Cc: linux-renesas-soc@vger.kernel.org
Cc: linux-rockchip@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-tegra@vger.kernel.org
Cc: xen-devel@lists.xen.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190117210334.13234-1-daniel.vetter@ffwll.ch

It occurred to me that we never actually check this! So let's start
doing that.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-20-lyude@redhat.com

There has been a TODO waiting for quite a long time in
drm_dp_mst_topology.c:

	/* We cannot rely on port->vcpi.num_slots to update
	 * topology_state->avail_slots as the port may not exist if the parent
	 * branch device was unplugged. This should be fixed by tracking
	 * per-port slot allocation in drm_dp_mst_topology_state instead of
	 * depending on the caller to tell us how many slots to release.
	 */

That's not the only reason we should fix this: forcing the driver to
track the VCPI allocations throughout a state's atomic check is
error prone, because it means that extra care has to be taken with the
order that drm_dp_atomic_find_vcpi_slots() and
drm_dp_atomic_release_vcpi_slots() are called in in order to ensure
idempotency. Currently the only driver actually using these helpers,
i915, doesn't even do this correctly: multiple ->best_encoder() checks
with i915's current implementation would not be idempotent and would
over-allocate VCPI slots, something I learned trying to implement
fallback retraining in MST.

So: simplify this whole mess, and teach drm_dp_atomic_find_vcpi_slots()
and drm_dp_atomic_release_vcpi_slots() to track the VCPI allocations for
each port. This allows us to ensure idempotency without having to rely
on the driver as much. Additionally: the driver doesn't need to do any
kind of VCPI slot tracking anymore if it doesn't need it for it's own
internal state.

Additionally; this adds a new drm_dp_mst_atomic_check() helper which
must be used by atomic drivers to perform validity checks for the new
VCPI allocations incurred by a state.

Also: update the documentation and make it more obvious that these
/must/ be called by /all/ atomic drivers supporting MST.

Changes since v9:
* Add some missing changes that were requested by danvet that I forgot
  about after I redid all of the kref stuff:
  * Remove unnecessary state changes in intel_dp_mst_atomic_check
  * Cleanup atomic check logic for VCPI allocations - all we need to check in
    compute_config is whether or not this state disables a CRTC, then free
    VCPI based off that

Changes since v8:
 * Fix compile errors, whoops!

Changes since v7:
 - Don't check for mixed stale/valid VCPI allocations, just rely on
 connector registration to stop such erroneous modesets

Changes since v6:
 - Keep a kref to all of the ports we have allocations on. This required
   a good bit of changing to when we call drm_dp_find_vcpi_slots(),
   mainly that we need to ensure that we only redo VCPI allocations on
   actual mode or CRTC changes, not crtc_state->active changes.
   Additionally, we no longer take the registration of the DRM connector
   for each port into account because so long as we have a kref to the
   port in the new or previous atomic state, the connector will stay
   registered.
 - Use the small changes to drm_dp_put_port() to add even more error
   checking to make misusage of the helpers more obvious. I added this
   after having to chase down various use-after-free conditions that
   started popping up from the new helpers so no one else has to
   troubleshoot that.
 - Move some accidental DRM_DEBUG_KMS() calls to DRM_DEBUG_ATOMIC()
 - Update documentation again, note that find/release() should both not be
   called on the same port in a single atomic check phase (but multiple
   calls to one or the other is OK)

Changes since v4:
 - Don't skip the atomic checks for VCPI allocations if no new VCPI
   allocations happen in a state. This makes the next change I'm about
   to list here a lot easier to implement.
 - Don't ignore VCPI allocations on destroyed ports, instead ensure that
   when ports are destroyed and still have VCPI allocations in the
   topology state, the only state changes allowed are releasing said
   ports' VCPI. This prevents a state with a mix of VCPI allocations
   from destroyed ports, and allocations from valid ports.

Changes since v3:
 - Don't release VCPI allocations in the topology state immediately in
   drm_dp_atomic_release_vcpi_slots(), instead mark them as 0 and skip
   over them in drm_dp_mst_duplicate_state(). This makes it so
   drm_dp_atomic_release_vcpi_slots() is still idempotent while also
   throwing warnings if the driver messes up it's book keeping and tries
   to release VCPI slots on a port that doesn't have any pre-existing
   VCPI allocation - danvet
 - Change mst_state/state in some debugging messages to "mst state"

Changes since v2:
 - Use kmemdup() for duplicating MST state - danvet
 - Move port validation out of duplicate state callback - danvet
 - Handle looping through MST topology states in
   drm_dp_mst_atomic_check() so the driver doesn't have to do it
 - Fix documentation in drm_dp_atomic_find_vcpi_slots()
 - Move the atomic check for each individual topology state into it's
   own function, reduces indenting
 - Don't consider "stale" MST ports when calculating the bandwidth
   requirements. This is needed because originally we relied on the
   state duplication functions to prune any stale ports from the new
   state, which would prevent us from incorrectly considering their
   bandwidth requirements alongside legitimate new payloads.
 - Add function references in drm_dp_atomic_release_vcpi_slots() - danvet
 - Annotate atomic VCPI and atomic check functions with __must_check
   - danvet

Changes since v1:
 - Don't use the now-removed ->atomic_check() for private objects hook,
   just give drivers a function to call themselves
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-19-lyude@redhat.com

Changes since v6:
 - Move EXPORT_SYMBOL() for drm_dp_mst_topology_state_funcs to this
   commit
 - Document __drm_dp_mst_state_iter_get() and note that it shouldn't be
   called directly
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-18-lyude@redhat.com

Up until now, freeing payloads on remote MST hubs that just had ports
removed has almost never worked because we've been relying on port
validation in order to stop us from accessing ports that have already
been freed from memory, but ports which need their payloads released due
to being removed will never be a valid part of the topology after
they've been removed.

Since we've introduced malloc refs, we can replace all of the validation
logic in payload helpers which are used for deallocation with some
well-placed malloc krefs. This ensures that regardless of whether or not
the ports are still valid and in the topology, any port which has an
allocated payload will remain allocated in memory until it's payloads
have been removed - finally allowing us to actually release said
payloads correctly.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-10-lyude@redhat.com

This has never actually worked, and isn't needed anyway: the driver's
always going to try to deallocate VCPI when it tears down the display
that the VCPI belongs to.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-9-lyude@redhat.com

While this isn't a complete fix, this will improve the reliability of
drm_dp_get_last_connected_port_and_mstb() pretty significantly during
hotplug events, since there's a chance that the in-memory topology tree
may not be fully updated when drm_dp_get_last_connected_port_and_mstb()
is called and thus might end up causing our search to fail on an mstb
whose topology refcount has reached 0, but has not yet been removed from
it's parent.

Ideally, we should further fix this problem by ensuring that we deal
with the potential for racing with a hotplug event, which would look
like this:

* drm_dp_payload_send_msg() retrieves the last living relative of mstb
  with drm_dp_get_last_connected_port_and_mstb()
* drm_dp_payload_send_msg() starts building payload message
  At the same time, mstb gets unplugged from the topology and is no
  longer the actual last living relative of the original mstb
* drm_dp_payload_send_msg() tries sending the payload message, hub times
  out
* Hub timed out, we give up and run away-resulting in the payload being
  leaked

This could be fixed by restarting the
drm_dp_get_last_connected_port_and_mstb() search whenever we get a
timeout, sending the payload to the new mstb, then repeating until
either the entire topology is removed from the system or
drm_dp_get_last_connected_port_and_mstb() fails. But since the above
race condition is not terribly likely, we'll address that in a later
patch series once we've improved the recovery handling for VCPI
allocations in the rest of the DP MST helpers.

Changes since v1:
* Convert kerneldoc for drm_dp_get_last_connected_port_and_mstb to
  normal comment - danvet
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-8-lyude@redhat.com

The current way of handling refcounting in the DP MST helpers is really
confusing and probably just plain wrong because it's been hacked up many
times over the years without anyone actually going over the code and
seeing if things could be simplified.

To the best of my understanding, the current scheme works like this:
drm_dp_mst_port and drm_dp_mst_branch both have a single refcount. When
this refcount hits 0 for either of the two, they're removed from the
topology state, but not immediately freed. Both ports and branch devices
will reinitialize their kref once it's hit 0 before actually destroying
themselves. The intended purpose behind this is so that we can avoid
problems like not being able to free a remote payload that might still
be active, due to us having removed all of the port/branch device
structures in memory, as per:

commit 91a25e46 ("drm/dp/mst: deallocate payload on port destruction")

Which may have worked, but then it caused use-after-free errors. Being
new to MST at the time, I tried fixing it;

commit 263efde3 ("drm/dp/mst: Get validated port ref in drm_dp_update_payload_part1()")

But, that was broken: both drm_dp_mst_port and drm_dp_mst_branch structs
are validated in almost every DP MST helper function. Simply put, this
means we go through the topology and try to see if the given
drm_dp_mst_branch or drm_dp_mst_port is still attached to something
before trying to use it in order to avoid dereferencing freed memory
(something that has happened a LOT in the past with this library).
Because of this it doesn't actually matter whether or not we keep keep
the ports and branches around in memory as that's not enough, because
any function that validates the branches and ports passed to it will
still reject them anyway since they're no longer in the topology
structure. So, use-after-free errors were fixed but payload deallocation
was completely broken.

Two years later, AMD informed me about this issue and I attempted to
come up with a temporary fix, pending a long-overdue cleanup of this
library:

commit c54c7374 ("drm/dp_mst: Skip validating ports during destruction, just ref")

But then that introduced use-after-free errors, so I quickly reverted
it:

commit 9765635b ("Revert "drm/dp_mst: Skip validating ports during destruction, just ref"")

And in the process, learned that there is just no simple fix for this:
the design is just broken. Unfortunately, the usage of these helpers are
quite broken as well. Some drivers like i915 have been smart enough to
avoid accessing any kind of information from MST port structures, but
others like nouveau have assumed, understandably so, that
drm_dp_mst_port structures are normal and can just be accessed at any
time without worrying about use-after-free errors.

After a lot of discussion, me and Daniel Vetter came up with a better
idea to replace all of this.

To summarize, since this is documented far more indepth in the
documentation this patch introduces, we make it so that drm_dp_mst_port
and drm_dp_mst_branch structures have two different classes of
refcounts: topology_kref, and malloc_kref. topology_kref corresponds to
the lifetime of the given drm_dp_mst_port or drm_dp_mst_branch in it's
given topology. Once it hits zero, any associated connectors are removed
and the branch or port can no longer be validated. malloc_kref
corresponds to the lifetime of the memory allocation for the actual
structure, and will always be non-zero so long as the topology_kref is
non-zero. This gives us a way to allow callers to hold onto port and
branch device structures past their topology lifetime, and dramatically
simplifies the lifetimes of both structures. This also finally fixes the
port deallocation problem, properly.

Additionally: since this now means that we can keep ports and branch
devices allocated in memory for however long we need, we no longer need
a significant amount of the port validation that we currently do.

Additionally, there is one last scenario that this fixes, which couldn't
have been fixed properly beforehand:

- CPU1 unrefs port from topology (refcount 1->0)
- CPU2 refs port in topology(refcount 0->1)

Since we now can guarantee memory safety for ports and branches
as-needed, we also can make our main reference counting functions fix
this problem by using kref_get_unless_zero() internally so that topology
refcounts can only ever reach 0 once.

Changes since v4:
* Change the kernel-figure summary for dp-mst/topology-figure-1.dot a
  bit - danvet
* Remove figure numbers - danvet

Changes since v3:
* Remove rebase detritus - danvet
* Split out purely style changes into separate patches - hwentlan

Changes since v2:
* Fix commit message - checkpatch
* s/)-1/) - 1/g - checkpatch

Changes since v1:
* Remove forward declarations - danvet
* Move "Branch device and port refcounting" section from documentation
  into kernel-doc comments - danvet
* Export internal topology lifetime functions into their own section in
  the kernel-docs - danvet
* s/@/&/g for struct references in kernel-docs - danvet
* Drop the "when they are no longer being used" bits from the kernel
  docs - danvet
* Modify diagrams to show how the DRM driver interacts with the topology
  and payloads - danvet
* Make suggested documentation changes for
  drm_dp_mst_topology_get_mstb() and drm_dp_mst_topology_get_port() -
  danvet
* Better explain the relationship between malloc refs and topology krefs
  in the documentation for drm_dp_mst_topology_get_port() and
  drm_dp_mst_topology_get_mstb() - danvet
* Fix "See also" in drm_dp_mst_topology_get_mstb() - danvet
* Rename drm_dp_mst_topology_get_(port|mstb)() ->
  drm_dp_mst_topology_try_get_(port|mstb)() and
  drm_dp_mst_topology_ref_(port|mstb)() ->
  drm_dp_mst_topology_get_(port|mstb)() - danvet
* s/should/must in docs - danvet
* WARN_ON(refcount == 0) in topology_get_(mstb|port) - danvet
* Move kdocs for mstb/port structs inline - danvet
* Split drm_dp_get_last_connected_port_and_mstb() changes into their own
  commit - danvet
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-7-lyude@redhat.com

s/drm_dp_get_validated_port_ref/drm_dp_mst_topology_get_port_validated/
s/drm_dp_put_port/drm_dp_mst_topology_put_port/
s/drm_dp_get_validated_mstb_ref/drm_dp_mst_topology_get_mstb_validated/
s/drm_dp_put_mst_branch_device/drm_dp_mst_topology_put_mstb/

This is a much more consistent naming scheme, and will make even more
sense once we redesign how the current refcounting scheme here works.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Reviewed-by: NDaniel Vetter <daniel@ffwll.ch>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Cc: David Airlie <airlied@redhat.com>
Cc: Jerry Zuo <Jerry.Zuo@amd.com>
Cc: Juston Li <juston.li@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-6-lyude@redhat.com