If the engine isn't being retired (worker starvation?) then it is
possible for us to repeatedly observe that between consecutive
hangchecks the seqno on the ring to be the same and there remain
unretired requests. Ignore these completely and only regard the engine
as busy for the purpose of hang detection (not stall detection) if there
are outstanding breadcrumbs.

In recent history we have looked at using both the request and seqno as
indication of activity on the engine, but that was reduced to just
inspecting seqno in commit cffa781e ("drm/i915: Simplify check for
idleness in hangcheck"). However, in commit dcff85c8 ("drm/i915:
Enable i915_gem_wait_for_idle() without holding struct_mutex"), I made
the decision to use the new common lockless function, under the
assumption that request retirement was more frequent than hangcheck and
so we would not have a stuck busy check. The flaw there was in
forgetting that we accumulate the hang score, and so successive checks
seeing a stuck request, albeit with the GPU advancing elsewhere and so
not necessary the same stuck request, would eventually trigger the hang.

Fixes: dcff85c8 ("drm/i915: Enable i915_gem_wait_for_idle()...")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160820145408.32180-1-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>

As we never need to directly access the pages we allocate for scratch and
the pagetables, and always remap them into the GTT through the dma
remapper, we do not need to limit the allocations to lowmem i.e. we can
pass in the __GFP_HIGHMEM flag to the page allocation.

For backwards compatibility, e.g. certain old GPUs not liking highmem
for certain functions that may be accidentally mapped to the scratch
page by userspace, keep the GMCH probe as only allocating from DMA32.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822074431.26872-3-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

As the scratch page is no longer shared between all VM, and each has
their own, forgo the small allocation and simply embed the scratch page
struct into the i915_address_space.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822074431.26872-2-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: NMika Kuoppala <mika.kuoppala@intel.com>

Just like with sysfs, we do some major overhaul.

Pass dev_priv instead of dev to all feature macros (IS_, HAS_,
INTEL_, etc.). This has the side effect that a bunch of functions
now get dev_priv passed instead of dev.

All calls to INTEL_INFO()->gen have been replaced with
INTEL_GEN().

We want access to to_i915(node->minor->dev) in a lot of places,
so add the node_to_i915() helper to accommodate for this.

Finally, we have quite a few cases where we get a void * pointer,
and need to cast it to drm_device *, only to run to_i915() on it.
Add cast_to_i915() to do this.

v2: Don't introduce extra dev (Chris)

v3: Make pipe_crc_info have a pointer to drm_i915_private instead of
    drm_device. This saves a bit of space, since we never use
    drm_device anywhere in these functions.

    Also some minor fixup that I missed in the previous version.

v4: Changed the code a bit so that dev_priv is passed directly
    to various functions, thus removing the need for the
    cast_to_i915() helper. Also did some additional cleanup.

v5: Additional cleanup of newly introduced changes.

v6: Rebase again because of conflict.
Signed-off-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822105931.pcbe2lpsgzckzboa@boomReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

In an effort to simplify things for a future push of dev_priv instead
of dev wherever possible, always take pdev via dev_priv where
feasible, eliminating the direct access from dev. Right now this
only eliminates a few cases of dev, but it also obviates that we pass
dev into a lot of functions where dev_priv would be the more obvious
choice.

v2: Fixed one more place missing in the previous patch set
Signed-off-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822103245.24069-5-david.weinehall@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Various cleanup for i915_sysfs.c; we now use dev_priv whenever
possible. The kdev_to_drm_minor() helper function has been
replaced by one that converts from struct device *
to struct drm_i915_private *.

We already have a seemingly identical helper (kdev_to_i915())
in i915_drv.h. But that one cannot be used here.
Unlike the version in i915_drv.h, this helper
reaches i915 through drm_minor.

v2: Rename kdev_to_i915_dm() to kdev_minor_to_i915() (Chris)
Signed-off-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822103245.24069-4-david.weinehall@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

We currently have a mix of struct device *device, struct device *kdev,
and struct device *dev (the latter forcing us to refer to
struct drm_device as something else than the normal dev).

To simplify things, always use kdev when referring to struct device.

v2: Replace the dev_to_drm_minor() macro with the inline function
    kdev_to_drm_minor().
Signed-off-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822103245.24069-3-david.weinehall@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Fix minor whitespace issues plus a typo.
Signed-off-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822103245.24069-2-david.weinehall@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Merge commit 5e580523 reverts the version bumping parts of
commit 4aa7fb9c. Bump the versions again and request the specific
firmware version.

The currently recommended versions are: SKL 1.26, KBL 1.01 and BXT 1.07.

Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97242
Cc: drm-intel-fixes@lists.freedesktop.org
Fixes: 5e580523 ("Backmerge tag 'v4.7' into drm-next")
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471266567-22443-1-git-send-email-maarten.lankhorst@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

If we're enabling a pipe, we'll need to modify the watermarks on all
active planes. Since those planes won't be added to the state on
their own, we need to add them ourselves.
Signed-off-by: NLyude <cpaul@redhat.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Cc: stable@vger.kernel.org
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-6-git-send-email-cpaul@redhat.com

When we write watermark values to the hardware, those values are stored
in dev_priv->wm.skl_hw.  However with recent watermark changes, the
results structure we're copying from only contains valid watermark and
DDB values for the pipes that are actually changing; the values for
other pipes remain 0.  Thus a blind copy of the entire skl_wm_values
structure will clobber the values for unchanged pipes...we need to be
more selective and only copy over the values for the changing pipes.

This mistake was hidden until recently due to another bug that caused us
to erroneously re-calculate watermarks for all active pipes rather than
changing pipes.  Only when that bug was fixed was the impact of this bug
discovered (e.g., modesets failing with "Requested display configuration
exceeds system watermark limitations" messages and leaving watermarks
non-functional, even ones initiated by intel_fbdev_restore_mode).

Changes since v1:
 - Add a function for copying a pipe's wm values
   (skl_copy_wm_for_pipe()) so we can reuse this later

Fixes: 734fa01f ("drm/i915/gen9: Calculate watermarks during atomic 'check' (v2)")
Fixes: 9b613022 ("drm/i915/gen9: Re-allocate DDB only for changed pipes")
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NLyude <cpaul@redhat.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Cc: stable@vger.kernel.org
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-4-git-send-email-cpaul@redhat.com

Since the watermark calculations for Skylake are still broken, we're apt
to hitting underruns very easily under multi-monitor configurations.
While it would be lovely if this was fixed, it's not. Another problem
that's been coming from this however, is the mysterious issue of
underruns causing full system hangs. An easy way to reproduce this with
a skylake system:

- Get a laptop with a skylake GPU, and hook up two external monitors to
  it
- Move the cursor from the built-in LCD to one of the external displays
  as quickly as you can
- You'll get a few pipe underruns, and eventually the entire system will
  just freeze.

After doing a lot of investigation and reading through the bspec, I
found the existence of the SAGV, which is responsible for adjusting the
system agent voltage and clock frequencies depending on how much power
we need. According to the bspec:

"The display engine access to system memory is blocked during the
 adjustment time. SAGV defaults to enabled. Software must use the
 GT-driver pcode mailbox to disable SAGV when the display engine is not
 able to tolerate the blocking time."

The rest of the bspec goes on to explain that software can simply leave
the SAGV enabled, and disable it when we use interlaced pipes/have more
then one pipe active.

Sure enough, with this patchset the system hangs resulting from pipe
underruns on Skylake have completely vanished on my T460s. Additionally,
the bspec mentions turning off the SAGV	with more then one pipe enabled
as a workaround for display underruns. While this patch doesn't entirely
fix that, it looks like it does improve the situation a little bit so
it's likely this is going to be required to make watermarks on Skylake
fully functional.

This will still need additional work in the future: we shouldn't be
enabling the SAGV if any of the currently enabled planes can't enable WM
levels that introduce latencies >= 30 µs.

Changes since v11:
 - Add skl_can_enable_sagv()
 - Make sure we don't enable SAGV when not all planes can enable
   watermarks >= the SAGV engine block time. I was originally going to
   save this for later, but I recently managed to run into a machine
   that was having problems with a single pipe configuration + SAGV.
 - Make comparisons to I915_SKL_SAGV_NOT_CONTROLLED explicit
 - Change I915_SAGV_DYNAMIC_FREQ to I915_SAGV_ENABLE
 - Move printks outside of mutexes
 - Don't print error messages twice
Changes since v10:
 - Apparently sandybridge_pcode_read actually writes values and reads
   them back, despite it's misleading function name. This means we've
   been doing this mostly wrong and have been writing garbage to the
   SAGV control. Because of this, we no longer attempt to read the SAGV
   status during initialization (since there are no helpers for this).
 - mlankhorst noticed that this patch was breaking on some very early
   pre-release Skylake machines, which apparently don't allow you to
   disable the SAGV. To prevent machines from failing tests due to SAGV
   errors, if the first time we try to control the SAGV results in the
   mailbox indicating an invalid command, we just disable future attempts
   to control the SAGV state by setting dev_priv->skl_sagv_status to
   I915_SKL_SAGV_NOT_CONTROLLED and make a note of it in dmesg.
 - Move mutex_unlock() a little higher in skl_enable_sagv(). This
   doesn't actually fix anything, but lets us release the lock a little
   sooner since we're finished with it.
Changes since v9:
 - Only enable/disable sagv on Skylake
Changes since v8:
 - Add intel_state->modeset guard to the conditional for
   skl_enable_sagv()
Changes since v7:
 - Remove GEN9_SAGV_LOW_FREQ, replace with GEN9_SAGV_IS_ENABLED (that's
   all we use it for anyway)
 - Use GEN9_SAGV_IS_ENABLED instead of 0x1 for clarification
 - Fix a styling error that snuck past me
Changes since v6:
 - Protect skl_enable_sagv() with intel_state->modeset conditional in
   intel_atomic_commit_tail()
Changes since v5:
 - Don't use is_power_of_2. Makes things confusing
 - Don't use the old state to figure out whether or not to
   enable/disable the sagv, use the new one
 - Split the loop in skl_disable_sagv into it's own function
 - Move skl_sagv_enable/disable() calls into intel_atomic_commit_tail()
Changes since v4:
 - Use is_power_of_2 against active_crtcs to check whether we have > 1
   pipe enabled
 - Fix skl_sagv_get_hw_state(): (temp & 0x1) indicates disabled, 0x0
   enabled
 - Call skl_sagv_enable/disable() from pre/post-plane updates
Changes since v3:
 - Use time_before() to compare timeout to jiffies
Changes since v2:
 - Really apply minor style nitpicks to patch this time
Changes since v1:
 - Added comments about this probably being one of the requirements to
   fixing Skylake's watermark issues
 - Minor style nitpicks from Matt Roper
 - Disable these functions on Broxton, since it doesn't have an SAGV
Signed-off-by: NLyude <cpaul@redhat.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-3-git-send-email-cpaul@redhat.com
[mlankhorst: ENOSYS -> ENXIO, whitespace fixes]

In order to add proper support for the SAGV, we need to be able to know
what the cause of a failure to change the SAGV through the pcode mailbox
was. The reasoning for this is that some very early pre-release Skylake
machines don't actually allow you to control the SAGV on them, and
indicate an invalid mailbox command was sent.

This also might come in handy in the future for debugging.

Changes since v1:
 - Add functions for interpreting gen6 mailbox error codes along with
   gen7+ error codes, and actually interpret those codes properly
 - Renamed patch to reflect new behavior
Signed-off-by: NLyude <cpaul@redhat.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471463761-26796-2-git-send-email-cpaul@redhat.com
[mlankhorst: -ENOSYS -> -ENXIO for checkpatch]

intel_fbc_pre_update() depends upon the new state being already pinned
in place in the Global GTT (primarily for both fencing which wants both
an offset and a fence register, if assigned). This requires the call to
intel_fbc_pre_update() be after intel_pin_and_fence_fb() - but commit
e8216e50 ("drm/i915/fbc: call intel_fbc_pre_update earlier during
page flips") moved the code way too much up in its attempt to call it
before the page flip.

v2 (from Paulo):
 - Point the original bad commit.
 - Add a comment to maybe prevent further regressions.

Fixes: e8216e50 ("drm/i915/fbc: call intel_fbc_pre_update earlier...")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1471462904-842-1-git-send-email-paulo.r.zanoni@intel.com
Cc: stable@vger.kernel.org

This issue here is (I think) purely theoretical, since a compiler
would need to be especially foolish to recompute the value of
i915_gem_request_completed right after it was already used. Hence the
additional barrier() is also not really a restriction.

But I believe this to be at least permissible, and since our rcu
trickery is a beast it's worth to annotate all the corner cases.
Chris proposed to instead just wrap a READ_ONCE around
request->fence.seqno in i915_gem_request_completed. But that has a
measurable impact on code size, and everywhere we hold a full
reference to the underlying request it's also not needed. And
personally I'd like to have just enough barriers and locking needed
for correctness, but not more - it makes it much easier in the future
to understand what's going on.

Since the busy ioctl has now fully embraced it's races there's no
point annotating it there too. We really only need it in
active_get_rcu, since that function _must_ deliver a correct snapshot
of the active fences (and not chase something else).

v2: Polish the comment a bit more (Chris).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1471856122-466-1-git-send-email-daniel.vetter@ffwll.ch

Since by design, if not entirely by practice, nothing is allowed to
access the scratch page we use to background fill the VM, then we do not
need to ensure that it is coherent between the CPU and GPU.
set_pages_uc() does a stop_machine() after changing the PAT, and that
significantly impacts upon context creation throughput.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822074431.26872-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

The passed in flag that distinguishes i915_gem_pin_display from
i915_gem_gtt is from node->info_ent->data not the data function
parameter.

Fixes: 6da84829 ("drm/i915: Focus debugfs/i915_gem_pinned to show...")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819115625.17688-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Very old numbers indicate this is a 66% improvement when remapping the
entire object for fence contention - due to the elimination of
track_pfn_insert and its strcmp.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Testcase: igt/gem_fence_upload/performance
Testcase: igt/gem_mmap_gtt
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-6-chris@chris-wilson.co.uk

As io_mapping.h now always allocates the struct, we can avoid that
allocation and extra pointer dance by embedding the struct inside
drm_i915_private
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-5-chris@chris-wilson.co.uk

Currently, we only allocate a structure to hold metadata if we need to
allocate an ioremap for every access, such as on x86-32. However, it
would be useful to store basic information about the io-mapping, such as
its page protection, on all platforms.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: linux-mm@kvack.org
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-4-chris@chris-wilson.co.uk

Only fbc1 is tied to using a fence. Later iterations of fbc are more
flexible and allow operation on unfenced frontbuffers.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-3-chris@chris-wilson.co.uk

If the frontbuffer doesn't have an associated fence, it will have a
fence reg of -1. If we attempt to OR in this register into the FBC
control register we end up setting all control bits, oops!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>
Reviwed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-2-chris@chris-wilson.co.uk

What I never hit in testing, but Mika immediately did, was a GPU hang
with a pending fence release (where a tiled object has been changed by
the user to be untiled, and the update has not yet been committed to the
fence register). As the stride/tiling is 0, this causes a divide-by-zero
error when trying to write the new fence parameters:

[   28.784518] drm/i915: Resetting chip after gpu hang
[   28.784551] divide error: 0000 [#1] PREEMPT SMP
[   28.784565] Modules linked in: nls_iso8859_1 nls_cp437 vfat fat mxm_wmi x86_pkg_temp_thermal snd_hda_codec_hdmi kvm irqbypass snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec serio_raw snd_hwdep snd_hda_core snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_timer snd_seq_device snd soundcore mac_hid wmi efivarfs autofs4 raid10 raid456 libcrc32c async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx raid0 multipath linear psmouse e1000e ptp pps_core nvme nvme_core i915 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm video
[   28.784738] CPU: 0 PID: 1692 Comm: kworker/0:2 Not tainted 4.8.0-rc2+ #895
[   28.784752] Hardware name: System manufacturer System Product Name/Z170M-PLUS, BIOS 1803 05/09/2016
[   28.784786] Workqueue: events_long i915_hangcheck_elapsed [i915]
[   28.784814] task: ffff923c18f59d40 task.stack: ffff923c1b7e4000
[   28.784827] RIP: 0010:[<ffffffffc0475b5f>]  [<ffffffffc0475b5f>] fence_write+0x9f/0x3b0 [i915]
[   28.784854] RSP: 0018:ffff923c1b7e7b30  EFLAGS: 00010246
[   28.784866] RAX: 00000000008ca000 RBX: ffff923c18540000 RCX: 0000000000000020
[   28.784880] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000596d000
[   28.784894] RBP: ffff923c1b7e7b68 R08: 0000000000000000 R09: 0000000000000000
[   28.784908] R10: 0000000000000000 R11: 00000000008ca000 R12: ffff923c1ef9d600
[   28.784921] R13: 0000000000100040 R14: 0000000000100044 R15: ffff923c18549908
[   28.784935] FS:  0000000000000000(0000) GS:ffff923c36c00000(0000) knlGS:0000000000000000
[   28.784951] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   28.784962] CR2: 00007f193373c893 CR3: 0000000419c78000 CR4: 00000000003406f0
[   28.784976] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   28.784990] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   28.785004] Stack:
[   28.785009]  000000000596c03b ffff923c1b7e7b68 ffff923c18549938 0000000000000009
[   28.785026]  ffff923c18540000 ffff923c18549280 ffff923c18547ce8 ffff923c1b7e7b90
[   28.785044]  ffffffffc04761f9 ffff923c18540000 ffff923c18547d00 ffff923c18548ff8
[   28.785062] Call Trace:
[   28.785078]  [<ffffffffc04761f9>] i915_gem_restore_fences+0x39/0x50 [i915]
[   28.785102]  [<ffffffffc047fe89>] i915_gem_reset+0x179/0x300 [i915]
Reported-by: NMika Kuoppala <mika.kuoppala@intel.com>
Fixes: 49ef5294 ("drm/i915: Move fence tracking from object to vma")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819155428.1670-1-chris@chris-wilson.co.uk

In the recent patch
bc3d6744 drm/i915: Allow userspace to request no-error-capture upon ...
the final version moved the flags and the associated #defines around
so they were adjacent; unfortunately, they ended up between a comment
and the thing (hw_id) to which the comment applies :(

So this patch reshuffles the comment and subject back together.

Also, as we're touching 'hw_id', let's change it from just 'unsigned'
to a fully-specified 'unsigned int', because some code checking tools
(including checkpatch) object to plain 'unsigned'.

Fixes: bc3d6744 ("drm/i915: Allow userspace to request no-error-capture...")
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1471616622-6919-1-git-send-email-david.s.gordon@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

If we need to use clflush to prepare our batch for reads from memory, we
can bypass the cache instead by using non-temporal copies.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.william.auld@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-39-chris@chris-wilson.co.uk

A significant proportion of the cmdparsing time for some batches is the
cost to find the register in the mmiotable. We ensure that those tables
are in ascending order such that we could do a binary search if it was
ever merited. It is.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-38-chris@chris-wilson.co.uk

If the command descriptor says to skip it, ignore checking for anyother
other conflict.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-37-chris@chris-wilson.co.uk

On the blitter (and in test code), we see long sequences of repeated
commands, e.g. XY_PIXEL_BLT, XY_SCANLINE_BLT, or XY_SRC_COPY. For these,
we can skip the hashtable lookup by remembering the previous command
descriptor and doing a straightforward compare of the command header.
The corollary is that we need to do one extra comparison before lookup
up new commands.

v2: Less magic mask (ok, it is still magic, but now you cannot see!)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-36-chris@chris-wilson.co.uk

The existing code's hashfunction is very suboptimal (most 3D commands
use the same bucket degrading the hash to a long list). The code even
acknowledge that the issue was known and the fix simple:

/*
 * If we attempt to generate a perfect hash, we should be able to look at bits
 * 31:29 of a command from a batch buffer and use the full mask for that
 * client. The existing INSTR_CLIENT_MASK/SHIFT defines can be used for this.
 */
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-35-chris@chris-wilson.co.uk

For simplicity, we want to continue using a contiguous mapping of the
command buffer, but we can reduce the number of vmappings we hold by
switching over to a page-by-page copy from the user batch buffer to the
shadow. The cost for saving one linear mapping is about 5% in trivial
workloads - which is more or less the overhead in calling kmap_atomic().
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-34-chris@chris-wilson.co.uk

The single largest factor in the overhead of parsing the commands is the
setup of the virtual mapping to provide a continuous block for the batch
buffer. If we keep those vmappings around (against the better judgement
of mm/vmalloc.c, which we offset by handwaving and looking suggestively
at the shrinker) we can dramatically improve the performance of the
parser for small batches (such as media workloads). Furthermore, we can
use the prepare shmem read/write functions to determine  how best we
need to clflush the range (rather than every page of the object).

The impact of caching both src/dst vmaps is +80% on ivb and +140% on byt
for the throughput on small batches. (Caching just the dst vmap and
iterating over the src, doing a page by page copy is roughly 5% slower
on both platforms. That may be an acceptable trade-off to eliminate one
cached vmapping, and we may be able to reduce the per-page copying overhead
further.) For *this* simple test case, the cmdparser is now within a
factor of 2 of ideal performance.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-33-chris@chris-wilson.co.uk

Since I have been using the BCS_TIMESTAMP to measure latency of
execution upon the blitter ring, allow regular userspace to also read
from that register. They are already allowed RCS_TIMESTAMP!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-32-chris@chris-wilson.co.uk

If the developer adds a register in the wrong order, we BUG during boot.
That makes development and testing very difficult. Let's be a bit more
friendly and disable the command parser with a big warning if the tables
are invalid.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-31-chris@chris-wilson.co.uk

Since commit 43566ded ("drm/i915: Broaden application of
set-domain(GTT)") we allowed objects to be in the GTT domain, but unbound.
Therefore removing the GTT cache domain when removing the GGTT vma is no
longer semantically correct.

An unfortunate side-effect is we lose the wondrously named
i915_gem_object_finish_gtt(), not to be confused with
i915_gem_gtt_finish_object()!
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Akash Goel <akash.goel@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-30-chris@chris-wilson.co.uk

We track the LRU access for eviction and bump the last access for the
user GGTT on set-to-gtt. When we do so we need to not only bump the
primary GGTT VMA but all partials as well. Similarly we want to
bump the last access tracking for when unpinning an object from the
scanout so that they do not get promptly evicted and hopefully remain
available for reuse on the next frame.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-29-chris@chris-wilson.co.uk

When using the aliasing ppgtt and pageflipping with the shrinker/eviction
active, we note that we often have to rebind the backbuffer before
flipping onto the scanout because it has an invalid alignment. If we
store the worst-case alignment required for a VMA, we can avoid having
to rebind at critical junctures.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-28-chris@chris-wilson.co.uk

The existing ABI says that scanouts are pinned into the mappable region
so that legacy clients (e.g. old Xorg or plymouthd) can write directly
into the scanout through a GTT mapping. However if the surface does not
fit into the mappable region, we are better off just trying to fit it
anywhere and hoping for the best. (Any userspace that is capable of
using ginormous scanouts is also likely not to rely on pure GTT
updates.) With the partial vma fault support, we are no longer
restricted to only using scanouts that we can pin (though it is still
preferred for performance reasons and for powersaving features like
FBC).

v2: Skip fence pinning when not mappable.
v3: Add a comment to explain the possible ramifications of not being
    able to use fences for unmappable scanouts.
v4: Rebase to skip over some local patches
v5: Rebase to defer until after we have unmappable GTT fault support
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Deepak S <deepak.s@linux.intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-27-chris@chris-wilson.co.uk

Often times we do not want to evict mapped objects from the GGTT as
these are quite expensive to teardown and frequently reused (causing an
equally, if not more so, expensive setup). In particular, when faulting
in a new object we want to avoid evicting an active object, or else we
may trigger a page-fault-of-doom as we ping-pong between evicting two
objects.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-26-chris@chris-wilson.co.uk

If FBC is set on a framebuffer that is unmapped, all GTT faults will be
from a partial mapping. Writes by the user through the partial VMA are
then untracked by the FBC and so we must use the ORIGIN_CPU when flushing
the I915_GEM_DOMAIN_GTT.

v2: Keep ORIGIN_CPU for set-to-domain(.write=CPU)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-25-chris@chris-wilson.co.uk