BDW is no longer flagged as preliminary hw, but without
i915.preliminary_hw_support module param set the logs are filled with
WARNs about it.

Just make semaphores off the BDW per-chip default for now.

CC: Ben Widawsky <ben@bwidawsk.net>
Reported-by: NSebastien Dufour <sebastien.dufour@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

For example if we get bug reports with similar error states and
suspend count is always 1, that might lead the Sherlocks to
right general direction.
Suggested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Just to be sure...
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This got lost when we shuffled around our internal branch and
GEN7_FEATURES macro. There were no HW changes to support FBC, so we just
need to set the flag.

v2: Don't allow FBC for any pipe but A on platforms with DDI. (Paulo)

Cc: Daisy Sun <daisy.sun@intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The power domains framework is internal to the i915 driver, so pass
drm_i915_private instead of drm_device to its functions.

Also remove a dangling intel_set_power_well() declaration.

No functional change.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A check of rps/rc6 state after i915_reset determined that the ring
MAX_IDLE registers were returned to their hardware defaults and that
the GEN6_PMIMR register was set to mask all interrupts. This change
restores those values to their pre-reset states by re-initializing
rps/rc6 in i915_reset. A full re-initialization was opted for versus
a targeted set of restore operations for simplicity and maintain-
ability. Note that the re-initialization is not done for Ironlake,
due to a past comment that it causes problems.

Also updated the rps initialization sequence to preserve existing
min/max values in the case of a re-init. We assume the values were
validated upon being set and do not do further range checking. The
debugfs interface for changing min/max was updated with range
checking to ensure this condition (already present in sysfs
interface).

v2: fix rps logging to output hw_max and hw_min, not rps.max_delay
    and rps.min_delay which don't strictly represent hardware limits.
    Add igt testcase to signed-off-by section.

Testcase: igt/pm_rps/reset
Signed-off-by: NJeff McGee <jeff.mcgee@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

RFCv2: Reorganize array indexing so that full offsets can be used as
is. It makes grepping for registers in i915_reg.h much easier. Also
move offset arrays to intel_device_info.

v1: Fixed offsets for VLV, proper eDP handling

v2: Fixed BCLRPAT, PIPESRC, PIPECONF and DSP* macros.

v3: Added EDP pipe comment, removed redundant offset arrays for
    MSA_MISC and DDI_FUNC_CTL.

v4: Rename patch and report object size increase.

v5: Change location of commas, add PIPE_EDP into enum pipe

v6: Insert PIPE_EDP_OFFSET into pipe offset array

v7: Set I915_MAX_PIPES back to 3, change more registers accessors
    to use the new macros, get rid of _PIPE_INC and add dev_priv
    as a parameter where required by the new macros.

Upcoming hardware will not have the various display pipe register
ranges evenly spaced in memory. Change register address calculations
into array lookups.

Tested on SNB, VLV, IVB, Gen2 and HSW w/eDP.

I left the UMS cruft untouched.

Size differences:
   text    data     bss     dec     hex filename
 596431    4634      56  601121   92c21 i915.ko (new)
 593199    4634      56  597889   91f81 i915.ko (old)
Signed-off-by: NAntti Koskipaa <antti.koskipaa@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With 20+ module parameters, I think referring to them via a struct
improves clarity over just having a bunch of globals. While at it, move
the parameter initialization and definitions into a new file
i915_params.c to reduce clutter in i915_drv.c.

Apart from the ill-named i915_enable_rc6, i915_enable_fbc and
i915_enable_ppgtt parameters, for which we lose the "i915_" prefix
internally, the module parameters now look the same both on the kernel
command line and in code. For example, "i915.modeset".

The downsides of the change are losing static on a couple of variables
and not having the initialization and module_param_named() right next to
each other. On the other hand, all module parameters are now defined in
one place at i915_params.c. Plus you can do this to find all module
parameter references:

$ git grep "i915\." -- drivers/gpu/drm/i915

v2:
- move the definitions into a new file
- s/i915_params/i915/
- make i915_try_reset i915.reset, for consistency
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's unused, and nowadays specifying unknown parameters no longer
prevents modules from being loaded.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently we're doing the reset handling a bit late, and we're doing
it both in the driver load code and on resume. This makes it unusable
for e.g. resetting the panel power sequence state like Paulo wants to.

Instead of adding yet another single-use callback shuffle things
around:
- Output handling code is responsible to reset/init all state on its
  own at driver load time.
- We call the reset functions much earlier, before we start using any
  of the modeset code.

Compared to Paulo's new ->resume callback the only difference in
placement is that ->reset is still called without dev->struct_mutex
held. Which is imo a feature.

v2: Rebase on top of the now merge dinq.

Cc: Paulo Zanoni <przanoni@gmail.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The opregion notification for runtime suspend is currently D1, not D3.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It ought to work ok in 3.14.  We have some fun stuff coming after that,
but all the basics are in place now and seem relatively stable.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Acked by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A couple patches in the upcoming rework of semaphores will break if
semaphores are toggled by the user at various times. Since the code
cleanups there seem to be an overall win, and toggling semaphores at
runtime is not a terribly useful thing to do, simply make the module
parameter read-only.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

As with processes which run on the CPU, the goal of multiple VMs is to
provide process isolation. Specific to GEN, there is also the ability to
map more objects per process (2GB each instead of 2Gb-2k total).

For the most part, all the pipes have been laid, and all we need to do
is remove asserts and actually start changing address spaces with the
context switch. Since prior to this we've converted the setting of the
page tables to a streamed version, this is quite easy.

One important thing to point out (since it'd been hotly contested) is
that with this patch, every context created will have it's own address
space (provided the HW can do it).

v2: Disable BDW on rebase

NOTE: I tried to make this commit as small as possible. I needed one
place where I could "turn everything on" and that is here. It could be
split into finer commits, but I didn't really see much point.

Cc: Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Only the two intel drivers need this and they can easily check for
working agp support in their driver ->load callbacks.

This is the only reason why agp initialization could fail, so allows
us to rip out a bit of error handling code in the next patch.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Noticed while reviewing a patch and couldn't resist the OCD.
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

So we'll get a fault when someone tries to access the mmap, then we'll
wake up from D3.

v2: - Rebase
v3: - Use gtt active/inactive

Testcase: igt/pm_pc8/gem-mmap-gtt
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
[danvet: Add comment + WARN as discussed with Paulo on irc.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The hangcheck function requires the hardware to be working, and if
we're suspending we're going to put the HW in D3 state.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

All mobile gen2 and gen3 chipsets should have FBC1, and the code
should now handle them all. So just set has_fbc=true for all such
chipsets.

Note that fbc is still disabled by default for now.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that we are actually setting the device to the D3 state, we should
issue the notification.

The opregion spec says we should send the message before the adapter
is about to be placed in a lower power state, and after the adapter is
placed in a higher power state.

Jani originally wrote a similar patch for PC8, but then we discovered
that we were not really changing the PCI D states when
enabling/disabling PC8, so we had to postpone his patch.

v2: - Improve commit message, explaining the expected state.

v3: - Rebase.

Cc: Jani Nikula <jani.nikula@intel.com>
Credits-to: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com> (v2)
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch adds the initial infrastructure to allow a Runtime PM
implementation that sets the device to its D3 state. The patch just
adds the necessary callbacks and the initial infrastructure.

We still don't have any platform that actually uses this
infrastructure, we still don't call get/put in all the places we need
to, and we don't have any function to save/restore the state of the
registers. This is not a problem since no platform uses the code added
by this patch. We have a few people simultaneously working on runtime
PM, so this initial code could help everybody make their plans.

V2: - Move some functions to intel_pm.c
    - Remove useless pm_runtime_allow() call at init
    - Remove useless pm_runtime_mark_last_busy() call at get
    - Use pm_runtime_get_sync() instead of 2 calls
    - Add a WARN to check if we're really awake

V3: - Rebase.

V4: - Don't need to call pci_{save,restore}_state and
      pci_set_power_sate, since they're already called by the PCI
      layer
    - Remove wrong pm_runtime_enable() call at init_runtime_pm
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We call intel_modeset_setup_hw_state() along two paths, driver
load/resume and after a lid event notification. During initialisation of
the driver, it is imperative that we reset the config state. This
correctly sets up the initial connector statuses and prepares the
hardware for a thorough probing. However, during a lid event, we only
want to undo the damage caused by the bios by resetting our last known
mode. In this cirumstance, we do not want to clobber our desired state.

In order to try and keep sanity between the config state and our own
tracking, do the drm_mode_config_reset() first along the load/resume
paths before reading out the hw state and apply any definite known
corrections.

v2: "As discussed on irc I don't think we should force the connector
state to anything here: Imo connector->status should reflect what we
believe to be the true output connection state, whereas connector->encoder
reflects whether this connector is wired up to a pipe. And since we no
longer reject modeset on disconnected connectors and never nuked the pipe
if the connector gets disconnected there's no reason for that - such policy
is userspace's job.

This regression has been introduced in

commit 2e938892
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 11 20:08:24 2012 +0200

    drm/i915/crt: explicitly set up HOTPLUG_BITS on resume"
so sayeth Daniel.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org (v3.8 and later)
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is just a theoretical issue, but we need to do this to prevent the
WARN in pipe_from_connector at suspend time.

This regression has been introduce in

commit 7bd688cd
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Fri Nov 8 16:48:56 2013 +0200

    drm/i915: handle backlight through chip specific functions

https://bugs.freedesktop.org/show_bug.cgi?id=71978Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This would have never worked.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Oops, makes testing early boot failures in i915.ko a bit more pain, so
let's fix it.

v2: We already have a bit of static storage to track this (Chris).
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At least since SNB (perhaps even earlier) even the desktop parts
should have FBC.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's been 5 years since kms support was merged and roughly 4 years
since UMS support was ripped out from userspace drivers.

Thus far it's not been a big burden to keep the ums paths alive, and
we've made some good progress in better separating it from the kms
code by sprinkling DRIVER_MODESET checks all over the place.

But now that the drm demidlayering is within reach this changes. I
want to make the driver loading code more robust using devres.c and
other cool tricks. But that doesn't work with ums due to the
shadow-attach trick. Which means we either
a) need to split out a complete ums codebase like radeon has
b) kill it for good.

The 2nd option is obviously much less work than the first, so I think
it's time to test the waters and see how many people out there still
use ums.

I've decided that silently failing to initialize the driver (and not
e.g. failing to load the module) is the right thing. That way we
should only get reports from users that actually care about some ums
features (like accelerated gl or support for secondary outputs).
Everyone else will just fall back to the vesa X driver.

For developers there's a small info level dmesg output.

The plan is to drop this Kconfig option after 3.16 (so gives us 2 full
releases) and then start killing code for real 2-3 releases
afterwards. That should be more than enough time for users to pipe up.

Of course if anyone does we need to revisit this plan and maybe go
with option a) above.

Also enable the KMS support by default in Kconfig and polish the help
texts a bit.

v2: Add the missing hunk of actual code changes. Oops. (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Acked-by: NDave Airlie <airlied@gmail.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Thus far we've tried to carefully work around the fact that old
userspace relied on the AGP-backed legacy buffer mapping ioctls for a
bit too long. But it's really horribly, and now some new users for it
started to show up again:

http://www.mail-archive.com/mesa-dev@lists.freedesktop.org/msg45547.html

This uses drmAgpSize to figure out the GTT size, which is both the
wrong thing to inquire and also might force us to keep this crap
around for another few years.

So I want to stop this particular zombie from raising ever again. Now
it's only been 4 years since XvMC was fixed for gen3, so a bit early
by the usual rules. But since Linus explicitly said that an ABI
breakage only counts if someone actually observes it I want to tempt
fate an accelarate the demise of AGP.

We probably need to wait 2-3 kernel releases with this shipping until
we go on a killing spree code-wise.

v2: Remove intel_agp_enabled since it's unused (Ville).

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Acked-by: NDave Airlie <airlied@gmail.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Most platforms din't hit this condition, but if we want to allow
building without agp we should also make this allowed on gen3.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We don't want any ERROR for simulated gpu hangs, otoh printing the
error code when the reset failed for real should be interesting.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71333
lu hua <huax.lu@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We only depend on the intel-gtt module for GTT frobbign on older gens.
The intel_agp module is optional, except for UMS and some old XvMC
userland on gen3. So make AGP support optional. As before, we will
fail the i915 init for UMS and gen3 KMS the same as before if
intel_agp isn't around.

intel-gtt.c is left with a somewhat ugly ifdef mess, but I'm going
to save that for a later cleaning.

At least my gen2 still works with the patch and CONFIG_AGP=n.

v2: Make i915 depend on X86 and PCI, and intel-gtt depend on PCI
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Early platforms use the same PCH as HSW, and to avoid triggering the
!ULT, and !HSW warnings, simply put it first in the search.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We've done insufficient testing on them thus far, so keep them disabled
until we do test.

v2: Use WARN when not enabling preliminary HW support as this should
only be disabled for that case.

v3: Rip out the now useless (and really noisy) DRM_INFO output.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NJesse Barnes <jbarnes@virtuosugeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The platforms we currently have all have LPT LP on them. As such, we
have no way to identify the new WPT PCH that will ship with Broadwell.

NOTE: For all purposes relevant to the driver that this point, LPT and
WPT are equivalent. Therefore there should be no need to actually change
this for some time.

v2: Don't assign dev_priv->num_pch_pll any more.

v3: Rebase on top of the PCH detection changes for virtualized
enviroments.

v4: Wrote commit message

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v3)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Rebase (Paulo Zanoni)

v3: Rebase on top of num_pipes having moved to intel_device_info.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> (v1)
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> (v2)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Squash in "drm/i915/bdw: Add BDW to the HAS_DDI check" as
suggested by Damien.

v3: Squash in VEBOX enabling from  Zhao Yakui <yakui.zhao@intel.com>

v4: Rebase on top of Jesse's patch to extract all pci ids to
include/drm/i915_pciids.h.

v4: Replace Halo by its marketing moniker Iris. Requested by Ben.

v5: Switch from info->has*ring to info->ring_mask.

v6: Add 0x16X2 variant (which is newer than this patch)
Rename to use new naming scheme (Chris)
Remove Simulator PCI ids. These snuck in during rebase (Chris)

v7: Fix poor sed job from v6
Make the desktop variants use the desktop macro (Rebase error). Notice
that this makes no functional difference - it's just confusing.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Fixed the botched locking on init_hw failure in i915_reset (Ville)
Call cleanup_ringbuffer on failed context create in init_hw (Ville)

v3: Add dev argument ti clean_ringbuffer
Reviewed-by: NKenneth Graunke <kenneth@whitecape.org>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Similarly rename the other related functions in the power domain
interface.

Higher level driver code calling these functions knows only about power
domains, not the underlying power wells which may be different on
different platforms. Also these functions really init/cleanup/resume
power domains and only through that all related power wells, so rename
them accordingly.

Note that I left i915_{request,release}_power_well as is, since that
really changes the state only of a single power well (and is HSW
specific). It should also get a better name once we make it more
generic by controlling things through a new audio power domain.

v4:
- use intel prefix instead of i915 everywhere (Paulo)
- use a $prefix_$block_$action format (Daniel)
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently we make sure that all power domains are enabled during driver
init and turn off unneded ones only after the first modeset. Similarly
during suspend we enable all power domains, which will remain on through
the following resume until the first modeset.

This logic is supported by intel_set_power_well() in the power domain
framework. It would be nice to simplify the API, so that we only have
get/put functions and make it more explicit on the higher level how this
"power well on during init" logic works. This will make it also easier
if in the future we want to shorten the time the power wells are on.

For this add a new device private flag tracking whether we have the
power wells on because of init/suspend and use only
intel_display_power_get()/put(). As nothing else uses
intel_set_power_well() we can remove it.

This also fixes

commit 6efdf354
Author: Imre Deak <imre.deak@intel.com>
Date:   Wed Oct 16 17:25:52 2013 +0300

    drm/i915: enable only the needed power domains during modeset

where removing intel_set_power_well() resulted in not releasing the
reference on the power well that was taken during init and thus leaving
the power well on all the time. Regression reported by Paulo.

v2:
- move the init_power_on flag to the power_domains struct (Daniel)

v3:
- add note about this being a regression fix too (Paulo)
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Once the machine gets to a certain point in the suspend process, we
expect the GPU to be idle. If it is not, we might corrupt memory.
Empirically (with an early version of this patch) we have seen this is
not the case. We cannot currently explain why the latent GPU writes
occur.

In the technical sense, this patch is a workaround in that we have an
issue we can't explain, and the patch indirectly solves the issue.
However, it's really better than a workaround because we understand why
it works, and it really should be a safe thing to do in all cases.

The noticeable effect other than the debug messages would be an increase
in the suspend time. I have not measure how expensive it actually is.

I think it would be good to spend further time to root cause why we're
seeing these latent writes, but it shouldn't preclude preventing the
fallout.

NOTE: It should be safe (and makes some sense IMO) to also keep the
VALID bit unset on resume when we clear_range(). I've opted not to do
this as properly clearing those bits at some later point would be extra
work.

v2: Fix bugzilla link

Bugzilla: http://bugs.freedesktop.org/show_bug.cgi?id=65496
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=59321Tested-by: NTakashi Iwai <tiwai@suse.de>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Tested-By: NTodd Previte <tprevite@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>