In order to ensure seqno/irq coherency, we currently read a ring register.
The mmio transaction following the interrupt delays the inspection of
the seqno long enough for the MI_STORE_DWORD_IMM to update the CPU
cache. However, it is only the memory timing that is important for the
purposes of the delay, we do not need nor desire the extra forcewake.

v3: Update commentary
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> [v2]
Link: http://patchwork.freedesktop.org/patch/msgid/1460195877-20520-1-git-send-email-chris@chris-wilson.co.uk

Currently for the case where there is enough space at the end of Ring
buffer for accommodating only the base request, the wrapround is done
immediately and as a result the base request gets added at the start
of Ring buffer. But there may not be enough free space at the beginning
to accommodate the base request, as before the wraparound, the wait was
effectively done for the reserved_size free space from the start of
Ring buffer. In such a case there is a potential of Ring buffer overflow,
the instructions at the head of Ring (ACTHD) can get overwritten.

Since the base request can fit in the remaining space, there is no need
to wraparound immediately. The wraparound will anyway happen later when
the reserved part starts getting used.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1457688402-10411-1-git-send-email-akash.goel@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org

Having fixed the tracking of the engine's last_submitted_seqno, we can
now rely on it for detecting when the engine is idle (and not have to
touch the requests pointer).

Testcase: igt/gem_exec_whisper
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-9-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>

Seal the request and mark it as pending execution before we submit it to
hardware. We assume that the actual submission cannot fail (that
guarantee is provided by preallocating space in the request for the
submission). As we may inspect this state without holding any locks
during hangcheck we should apply a barrier to ensure that we do
not see a more recent value in the HWS than we are tracking.

Based on a patch by Mika Kuoppala.
Suggested-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-8-git-send-email-chris@chris-wilson.co.ukReviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>

When we change the current seqno, we also need to remember to reset the
last_submitted_seqno for the engine.

Testcase: igt/gem_exec_whisper
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-7-git-send-email-chris@chris-wilson.co.uk

An oversight is that when we wrap the seqno, we need to reset the hw
semaphore counters to 0. We did this for gen6 and gen7 and forgot to do
so for the new implementation required for gen8 (legacy).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-6-git-send-email-chris@chris-wilson.co.uk

We reuse the same calculation into two macros, and I want to add a third
user. Time to refactor.
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/1460010558-10705-5-git-send-email-chris@chris-wilson.co.uk

Since we are setting engine local values that are tied to the hardware,
move it out of i915_gem_init_seqno() into the intel_ring_init_seqno()
backend, next to where the other hw semaphore registers are written.

v2: Make the explanatory comment about always resetting the semaphores to
0 irrespective of the value of the reset seqno.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-4-git-send-email-chris@chris-wilson.co.uk

We only use drm_i915_private within the function, so delete the unneeded
drm_device local.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-3-git-send-email-chris@chris-wilson.co.uk

After the GPU reset and we discard all of the incomplete requests, mark
the GPU as having advanced to the last_submitted_seqno (as having
completed the requests and ready for fresh work). The impact of this is
negligible, as all the requests will be considered completed by this
point, it just brings the HWS into line with expectations for external
viewers.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-2-git-send-email-chris@chris-wilson.co.uk

It's useful to look at the last seqno submitted on a particular engine
and compare it against the HWS value to check for irregularities.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460010558-10705-1-git-send-email-chris@chris-wilson.co.uk

At BXT DSI, PIPE registers are inactive. So we can't get the
PIPE's mode parameters from them. The possible option is
retriving them from the PORT registers.

The required changes are added for BXT in intel_dsi_get_config
(encoder->get_config).

v2: Addressed the Jani's comments
    -removed the redundant call to encoder->get_config
    -read bpp from port register
    -removed retrival of src_size from encoder->get_config

v3: pipe_config->pipe_bpp is fixed
    Jani's review comments addressed:
	Few horizontal timing parameters dropped from the patch to make
	progress, as there seems to be some disagreement on
	best/feasible/possible options.
Signed-off-by: NRamalingam C <ramalingam.c@intel.com>
Signed-off-by: NUma Shankar <uma.shankar@intel.com>

Previously Reviewed at: https://lists.freedesktop.org/archives/intel-gfx/2016-April/091737.htmlSigned-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460019967-26501-2-git-send-email-ramalingam.c@intel.com

Shared the function pixel_format_from_vbt for whole display module.
Function declaration is added to intel_dsi.h.

V2: Moved the function to intel_dsi.c and renamed as per the purpose
	of the function. Suggested by Jani.
Signed-off-by: NRamalingam C <ramalingam.c@intel.com>

Previously reviewed at https://lists.freedesktop.org/archives/intel-gfx/2016-April/091736.htmlSigned-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460019967-26501-1-git-send-email-ramalingam.c@intel.com

The shorthand is easier. Also change the struct name. No functional
changes.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/6572c108424a67b02367ea69cbbe00a03af9b958.1459884518.git.jani.nikula@intel.com

Prepare for future. No functional changes.

v2: Move earlier in the series. Use bool for gpio value.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
[Jani: restored fixme comment while applying.]
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/ee791fed271d7f31c34163de6c6be37d1b704ef3.1459884518.git.jani.nikula@intel.com

Define and store the pad base offset in the array, and reference the
pconf0 and padval registers through macros. Add VLV prefixes to
macros. Use spec nomenclature for pconf0 and padval.

v2: Address Ville's review comments, squash another patch here.

v3: Use the names Ville dug up in the specs.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/34932140b78a3de7f825c78380a08c930694651b.1459884518.git.jani.nikula@intel.com

dev_priv is what the macro works hard to extract, pass it directly.

> sed 's/\([A-Z].*(dev_priv\)->dev)/\1)/g'

v2:
- Include all wrapper macros too (Chris)

v3:
- Include sed cmdline (Chris)

v4:
- Break long line
- Rebase

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460016485-8089-1-git-send-email-joonas.lahtinen@linux.intel.com

According to Chris, use of i915_vm_to_ppgtt is visible in benchmark
unless WARN_ON is removed, so lets get rid of it.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Looks much better without container_of everywhere.

v2:
- In i915_gem_restore_gtt_mappings too (Chris)

v3:
- Do not cause WARN by calling on non PPGTT object (Chris)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

intel_update_max_cdclk() doesn't have a switch case for Broxton, so
dev_priv->max_cdclk_freq gets set to whatever clock frequency we're
currently running at (e.g., 144 MHz) rather than the true maximum.  This
causes our max dotclock to also be set too low and in turn leads mode
verification to reject perfectly valid modes while loading EDID firmware
blobs.

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459892239-14041-1-git-send-email-matthew.d.roper@intel.com

Use plane size for relative data rate calculation. don't always use
pipe source width & height.
adjust height & width according to rotation.
use plane size for watermark calculations also.

v2: Address Matt's comments.
    Use intel_plane_state->visible to avoid divide-by-zero error.
    Where FB was present but not visible so causing total data rate to
    be zero, hence divide-by-zero.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93917
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94044
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: NKumar, Mahesh <mahesh1.kumar@intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459956399-1296-1-git-send-email-matthew.d.roper@intel.com

This patch sets the invert bit for hpd detection for each port
based on VBT configuration. Since each AOB can be designed to
depend on invert bit or not, it is expected if an AOB requires
invert bit, the user will set respective bit in VBT.

v2: Separated VBT parsing from the rest of the logic. (Jani)

v3: Moved setting invert bit logic to bxt_hpd_irq_setup()
    and changed its logic to avoid looping twice. (Ville)

v4: Changed the logic to mask out the bits first and then
    set them to remove need of temporary variable. (Ville)

v5: Moved defines to existing set of defines for the register
    and added required breaks. (Ville)
Signed-off-by: NSivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: NDurgadoss R <durgadoss.r@intel.com>
Signed-off-by: NShubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
[Jani: fixed some checkpatch noise, added kernel-doc.]
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459420907-11383-2-git-send-email-shubhangi.shrivastava@intel.com

This patch adds new fields that are not yet added in drm code
in child devices struct
Signed-off-by: NSivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: NDurgadoss R <durgadoss.r@intel.com>
Signed-off-by: NShubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459420907-11383-1-git-send-email-shubhangi.shrivastava@intel.com

Currently we set the initial GPU frequency to min_freq_softlimit
on gen9, and to efficient_freq on VLV/CHV. On all the other platforms
we set it to idle_freq. Let's use idle_freq across the board to make
sure we don't waste power. This is especially relevant for VLV since
Vnn won't drop to minimum unless the GPU is at the minimum frequency.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457120584-26080-3-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

Extract the GPLL reference frequency from CCK and use it in the
GPU freq<->opcode conversions on VLV/CHV. This eliminates all the
assumptions we have about which divider is used for which czclk
frequency.

Note that unlike most clocks from CCK, the GPLL ref clock is a divided
down version of the CZ clock rather than the HPLL clock. CZ clock itself
is a divided down version of the HPLL clock though, so in effect it just
gets divided down twice.

While at it, throw in a few comments explaining the remaining constants
for anyone who later wants to compare this to the spreadsheets.

v2: Add slow/fast notes for CHV clocks (Imre)
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457120584-26080-2-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com> (v1)

After a suspend-resume cycle, the resumed kernel has no idea what the
booted kernel may have done to the GuC before replacing itself with the
resumed image. In particular, it may have already loaded the GuC with
firmware, which will then cause this kernel's attempt to (re)load the
firmware to fail (GuC program memory is write-once!). The symptoms
(GuC firmware reload fails after hibernation) are further described
in the Bugzilla reference below.

So let's *always* reset the GuC just before (re)loading the firmware;
the hardware should then be in a well-known state, and we may even
avoid some of the issues arising from unpredictable timing.

Also added some more fields & values to the definition of the GUC_STATUS
register, which is the key diagnostic indicator if the GuC load fails.
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Cc: Alex Dai <yu.dai@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94390Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

Due to timing issues in the HW, some of the status bits required for GuC
authentication occasionally don't get set; when that happens, the GuC
cannot be initialized and we will be left with a wedged GPU. The W/A
suggested is to perform a soft reset of the GuC and attempt to reload
the F/W again for few times before giving up.

As the failure is dependent on timing, tests performed by triggering
manual full gpu reset (i915_wedged) showed that we could sometimes hit
this after several thousand iterations, but sometimes tests ran even
longer without any issues. Reset and reload mechanism proved helpful
when we indeed hit f/w load failure, so it is better to include this
to improve driver stability.

This change implements the following WAs,

	WaEnableuKernelHeaderValidFix:skl,bxt
	WaEnableGuCBootHashCheckNotSet:skl,bxt
Signed-off-by: NArun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: NDave Gordon <david.s.gordon@intel.com>
Reviewed-by: NAlex Dai <yu.dai@intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

Both the oom and vmap notifier callbacks have a loop to acquire the
struct_mutex and set the device as uninterruptible, within a certain
time. Refactor the common code into a pair of functions.
Suggested-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459848145-24042-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

If the core runs out of vmap address space, it will call a notifier in
case any driver can reap some of its vmaps. As i915.ko is possibily
holding onto vmap address space that could be recovered, hook into the
notifier chain and try and reap objects holding onto vmaps.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Roman Pen <r.peniaev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kahola <mika.kahola@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459777603-23618-4-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Since we only attempt to purge an object if can_release_pages() report
true, we should also only add it to the count of potential recoverable
pages when can_release_pages() is true.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Akash Goel <akash.goel@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459777603-23618-2-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/65d58c578adecc205a741102329bc9c9f6eb79cf.1458299160.git.jani.nikula@intel.com

In sequence block v2, and only in v2, the gpio source (i.e. IOSF port)
is specified separately.

v2: initialize gpio_source to 0 and handle v1 and v2 in the same branch
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/87152feec8f921dc82502af1b29c0956b0d360bb.1458299160.git.jani.nikula@intel.com

Doing a lot of work in the interrupt handler introduces huge
latencies to the system as a whole.

Most dramatic effect can be seen by running an all engine
stress test like igt/gem_exec_nop/all where, when the kernel
config is lean enough, the whole system can be brought into
multi-second periods of complete non-interactivty. That can
look for example like this:

 NMI watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [kworker/u8:3:143]
 Modules linked in: [redacted for brevity]
 CPU: 0 PID: 143 Comm: kworker/u8:3 Tainted: G     U       L  4.5.0-160321+ #183
 Hardware name: Intel Corporation Broadwell Client platform/WhiteTip Mountain 1
 Workqueue: i915 gen6_pm_rps_work [i915]
 task: ffff8800aae88000 ti: ffff8800aae90000 task.ti: ffff8800aae90000
 RIP: 0010:[<ffffffff8104a3c2>]  [<ffffffff8104a3c2>] __do_softirq+0x72/0x1d0
 RSP: 0000:ffff88014f403f38  EFLAGS: 00000206
 RAX: ffff8800aae94000 RBX: 0000000000000000 RCX: 00000000000006e0
 RDX: 0000000000000020 RSI: 0000000004208060 RDI: 0000000000215d80
 RBP: ffff88014f403f80 R08: 0000000b1b42c180 R09: 0000000000000022
 R10: 0000000000000004 R11: 00000000ffffffff R12: 000000000000a030
 R13: 0000000000000082 R14: ffff8800aa4d0080 R15: 0000000000000082
 FS:  0000000000000000(0000) GS:ffff88014f400000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fa53b90c000 CR3: 0000000001a0a000 CR4: 00000000001406f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Stack:
  042080601b33869f ffff8800aae94000 00000000fffc2678 ffff88010000000a
  0000000000000000 000000000000a030 0000000000005302 ffff8800aa4d0080
  0000000000000206 ffff88014f403f90 ffffffff8104a716 ffff88014f403fa8
 Call Trace:
  <IRQ>
  [<ffffffff8104a716>] irq_exit+0x86/0x90
  [<ffffffff81031e7d>] smp_apic_timer_interrupt+0x3d/0x50
  [<ffffffff814f3eac>] apic_timer_interrupt+0x7c/0x90
  <EOI>
  [<ffffffffa01c5b40>] ? gen8_write64+0x1a0/0x1a0 [i915]
  [<ffffffff814f2b39>] ? _raw_spin_unlock_irqrestore+0x9/0x20
  [<ffffffffa01c5c44>] gen8_write32+0x104/0x1a0 [i915]
  [<ffffffff8132c6a2>] ? n_tty_receive_buf_common+0x372/0xae0
  [<ffffffffa017cc9e>] gen6_set_rps_thresholds+0x1be/0x330 [i915]
  [<ffffffffa017eaf0>] gen6_set_rps+0x70/0x200 [i915]
  [<ffffffffa0185375>] intel_set_rps+0x25/0x30 [i915]
  [<ffffffffa01768fd>] gen6_pm_rps_work+0x10d/0x2e0 [i915]
  [<ffffffff81063852>] ? finish_task_switch+0x72/0x1c0
  [<ffffffff8105ab29>] process_one_work+0x139/0x350
  [<ffffffff8105b186>] worker_thread+0x126/0x490
  [<ffffffff8105b060>] ? rescuer_thread+0x320/0x320
  [<ffffffff8105fa64>] kthread+0xc4/0xe0
  [<ffffffff8105f9a0>] ? kthread_create_on_node+0x170/0x170
  [<ffffffff814f351f>] ret_from_fork+0x3f/0x70
  [<ffffffff8105f9a0>] ? kthread_create_on_node+0x170/0x170

I could not explain, or find a code path, which would explain
a +20 second lockup, but from some instrumentation it was
apparent the interrupts off proportion of time was between
10-25% under heavy load which is quite bad.

When a interrupt "cliff" is reached, which was >~320k irq/s on
my machine, the whole system goes into a terrible state of the
above described multi-second lockups.

By moving the GT interrupt handling to a tasklet in a most
simple way, the problem above disappears completely.

Testing the effect on sytem-wide latencies using
igt/gem_syslatency shows the following before this patch:

gem_syslatency: cycles=1532739, latency mean=416531.829us max=2499237us
gem_syslatency: cycles=1839434, latency mean=1458099.157us max=4998944us
gem_syslatency: cycles=1432570, latency mean=2688.451us max=1201185us
gem_syslatency: cycles=1533543, latency mean=416520.499us max=2498886us

This shows that the unrelated process is experiencing huge
delays in its wake-up latency. After the patch the results
look like this:

gem_syslatency: cycles=808907, latency mean=53.133us max=1640us
gem_syslatency: cycles=862154, latency mean=62.778us max=2117us
gem_syslatency: cycles=856039, latency mean=58.079us max=2123us
gem_syslatency: cycles=841683, latency mean=56.914us max=1667us

Showing a huge improvement in the unrelated process wake-up
latency. It also shows an approximate halving in the number
of total empty batches submitted during the test. This may
not be worrying since the test puts the driver under
a very unrealistic load with ncpu threads doing empty batch
submission to all GPU engines each.

Another benefit compared to the hard-irq handling is that now
work on all engines can be dispatched in parallel since we can
have up to number of CPUs active tasklets. (While previously
a single hard-irq would serially dispatch on one engine after
another.)

More interesting scenario with regards to throughput is
"gem_latency -n 100" which  shows 25% better throughput and
CPU usage, and 14% better dispatch latencies.

I did not find any gains or regressions with Synmark2 or
GLbench under light testing. More benchmarking is certainly
required.

v2:
   * execlists_lock should be taken as spin_lock_bh when
     queuing work from userspace now. (Chris Wilson)
   * uncore.lock must be taken with spin_lock_irq when
     submitting requests since that now runs from either
     softirq or process context.

v3:
   * Expanded commit message with more testing data;
   * converted missed locking sites to _bh;
   * added execlist_lock comment. (Chris Wilson)

v4:
   * Mention dispatch parallelism in commit. (Chris Wilson)
   * Do not hold uncore.lock over MMIO reads since the block
     is already serialised per-engine via the tasklet itself.
     (Chris Wilson)
   * intel_lrc_irq_handler should be static. (Chris Wilson)
   * Cancel/sync the tasklet on GPU reset. (Chris Wilson)
   * Document and WARN that tasklet cannot be active/pending
     on engine cleanup. (Chris Wilson/Imre Deak)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Testcase: igt/gem_exec_nop/all
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94350Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1459768316-6670-1-git-send-email-tvrtko.ursulin@linux.intel.com

Silences

	src/drivers/gpu/drm/i915/intel_ddi.c: warning: 'port' may be used uninitialized in this function [-Wuninitialized]
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1459717154-27607-1-git-send-email-chris@chris-wilson.co.uk

As the current PCI power state is an essential feature of runtime pm,
include it in the debugfs/i915_runtime_pm_status.

v2: Use pci_power_name()
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1459689261-7920-2-git-send-email-chris@chris-wilson.co.uk

Since describe_obj() looks at state guarded by the struct_mutex, we need
to be holding it.

[  580.201054] drv_suspend: starting subtest debugfs-reader
[  580.239652] ------------[ cut here ]------------
[  580.239696] WARNING: CPU: 0 PID: 920 at include/linux/list_check.h:25 describe_obj+0x419/0x440()
[  580.239725] CPU: 0 PID: 920 Comm: cat Not tainted 4.5.0-rc6+ #835
[  580.239745] Hardware name:                  /NUC5CPYB, BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
[  580.239767]  0000000000000000 ffff88027554fcf8 ffffffff812c1135 0000000000000000
[  580.239815]  ffffffff8193dc42 ffff88027554fd30 ffffffff8107419d ffff880071727c00
[  580.239858]  ffff8802757d8000 ffffffff818f693c ffffffff818f693c ffff8802757b9048
[  580.239896] Call Trace:
[  580.239917]  [<ffffffff812c1135>] dump_stack+0x67/0x92
[  580.239939]  [<ffffffff8107419d>] warn_slowpath_common+0x7d/0xb0
[  580.239959]  [<ffffffff810742ba>] warn_slowpath_null+0x1a/0x20
[  580.239981]  [<ffffffff813ce579>] describe_obj+0x419/0x440
[  580.240006]  [<ffffffff813ced22>] i915_gem_framebuffer_info+0xa2/0x100
[  580.240033]  [<ffffffff811a9286>] seq_read+0xe6/0x3b0
[  580.240059]  [<ffffffff81182288>] __vfs_read+0x28/0xd0
[  580.240085]  [<ffffffff81173378>] ? SyS_fadvise64+0x228/0x2c0
[  580.240112]  [<ffffffff811823b2>] vfs_read+0x82/0x110
[  580.240137]  [<ffffffff811827d9>] SyS_read+0x49/0xa0
[  580.240162]  [<ffffffff815bac57>] entry_SYSCALL_64_fastpath+0x12/0x6b
[  580.240187] ---[ end trace 3e2cbf34576c9878 ]---
[  580.281900] ------------[ cut here ]------------
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1459689261-7920-1-git-send-email-chris@chris-wilson.co.uk

Deal with errors from drm_universal_plane_init() in primary and cursor
plane init paths (sprites were already covered). Also make the code
neater by using goto for error handling.

v2: Rebased due to drm_universal_plane_init() 'name' parameter
v3: Another rebase due to s/""/NULL/
v4: Rebased on drm-nightly (Matthew Auld)
v5: Fix email address (Matthew Auld)
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458571402-32749-1-git-send-email-matthew.auld@intel.com

VLV DPLL is somewhat sane and doesn't run on luck.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458052809-23426-7-git-send-email-ville.syrjala@linux.intel.comAcked-by: NJani Nikula <jani.nikula@intel.com>

Supposedly the power sequencer still locks out the DPLL registers on
CHV, so let's issue a warning if it's still locked when enabling the
DPLL.

Also drop the redundant IS_MOBILE() check for VLV when we check the same
thing.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458052809-23426-6-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Avoid redundant crtc->pipe lookups by giving vlv_enable_pll() a local
pipe variable. Also makes it look more like the corresponding CHV code.

While at is change the CHV code to enum pipe from int,
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458052809-23426-5-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>