[3.4-rc5, SNB] transaction abort when suspending

[3.4-rc5, SNB] transaction abort when suspending

[Daniel J Blueman]

At suspend time on 3.4-rc5 with SNB, we see a i915 register read
transaction aborted, presumably as the GT is powered down:

WARNING: at drivers/gpu/drm/i915/i915_drv.c:398
gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915]()
Hardware name: Latitude E5420
MMIO read or write has been dropped ffffffff
Modules linked in: brd dm_crypt dm_mod kvm_intel kvm coretemp
microcode uvcvideo videobuf2_core videodev videobuf2_vmalloc
videobuf2_memops iwlwifi binfmt_misc btrfs i915 cfbcopyarea video
cfbimgblt cfbfillrect
Pid: 23468, comm: kworker/u:13 Tainted: G        W    3.4.0-rc5-debug #10
Call Trace:
 [<ffffffff8103da3a>] warn_slowpath_common+0x7a/0xb0
 [<ffffffff8103db11>] warn_slowpath_fmt+0x41/0x50
 [<ffffffffa0020cd5>] ? i915_read32+0x65/0xb0 [i915]
 [<ffffffffa002055b>] gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915]
 [<ffffffffa00209e9>] __gen6_gt_force_wake_put+0x19/0x20 [i915]
 [<ffffffffa0020d09>] i915_read32+0x99/0xb0 [i915]
 [<ffffffffa0024275>] i915_update_gfx_val+0x85/0xe0 [i915]
 [<ffffffffa0041c4b>] intel_idle_update+0x4b/0xb0 [i915]
 [<ffffffff81058e96>] process_one_work+0x1b6/0x460
 [<ffffffff81058e38>] ? process_one_work+0x158/0x460
 [<ffffffffa0041c00>] ? intel_decrease_pllclock+0x130/0x130 [i915]
 [<ffffffff81059db4>] worker_thread+0x124/0x2d0
 [<ffffffff81059c90>] ? manage_workers.isra.25+0x120/0x120
 [<ffffffff8105ee3e>] kthread+0x8e/0xa0
 [<ffffffff815b6314>] kernel_thread_helper+0x4/0x10
 [<ffffffff81069977>] ? finish_task_switch+0x77/0x100
 [<ffffffff815b455b>] ? _raw_spin_unlock_irq+0x2b/0x50
 [<ffffffff815b49d9>] ? retint_restore_args+0xe/0xe
 [<ffffffff8105edb0>] ? __init_kthread_worker+0x70/0x70
 [<ffffffff815b6310>] ? gs_change+0xb/0xb

Thanks,
  Daniel
-- 
Daniel J Blueman

Re: [3.4-rc5, SNB] transaction abort when suspending

[Daniel Vetter]

On Thu, May 03, 2012 at 09:07:03PM +0800, Daniel J Blueman wrote:
> At suspend time on 3.4-rc5 with SNB, we see a i915 register read
> transaction aborted, presumably as the GT is powered down:
> 
> WARNING: at drivers/gpu/drm/i915/i915_drv.c:398
> gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915]()
> Hardware name: Latitude E5420
> MMIO read or write has been dropped ffffffff
> Modules linked in: brd dm_crypt dm_mod kvm_intel kvm coretemp
> microcode uvcvideo videobuf2_core videodev videobuf2_vmalloc
> videobuf2_memops iwlwifi binfmt_misc btrfs i915 cfbcopyarea video
> cfbimgblt cfbfillrect
> Pid: 23468, comm: kworker/u:13 Tainted: G        W    3.4.0-rc5-debug #10
> Call Trace:
>  [<ffffffff8103da3a>] warn_slowpath_common+0x7a/0xb0
>  [<ffffffff8103db11>] warn_slowpath_fmt+0x41/0x50
>  [<ffffffffa0020cd5>] ? i915_read32+0x65/0xb0 [i915]
>  [<ffffffffa002055b>] gen6_gt_check_fifodbg.isra.6+0x3b/0x50 [i915]
>  [<ffffffffa00209e9>] __gen6_gt_force_wake_put+0x19/0x20 [i915]
>  [<ffffffffa0020d09>] i915_read32+0x99/0xb0 [i915]
>  [<ffffffffa0024275>] i915_update_gfx_val+0x85/0xe0 [i915]
>  [<ffffffffa0041c4b>] intel_idle_update+0x4b/0xb0 [i915]
>  [<ffffffff81058e96>] process_one_work+0x1b6/0x460
>  [<ffffffff81058e38>] ? process_one_work+0x158/0x460
>  [<ffffffffa0041c00>] ? intel_decrease_pllclock+0x130/0x130 [i915]
>  [<ffffffff81059db4>] worker_thread+0x124/0x2d0
>  [<ffffffff81059c90>] ? manage_workers.isra.25+0x120/0x120
>  [<ffffffff8105ee3e>] kthread+0x8e/0xa0
>  [<ffffffff815b6314>] kernel_thread_helper+0x4/0x10
>  [<ffffffff81069977>] ? finish_task_switch+0x77/0x100
>  [<ffffffff815b455b>] ? _raw_spin_unlock_irq+0x2b/0x50
>  [<ffffffff815b49d9>] ? retint_restore_args+0xe/0xe
>  [<ffffffff8105edb0>] ? __init_kthread_worker+0x70/0x70
>  [<ffffffff815b6310>] ? gs_change+0xb/0xb

This is just ironlake code running on snb that shouldn't run on snb.
Otherwise no harmful side-effects known - the warning is newly added to
3.4. Patch to fix this is on track to get merged into 3.4-rc and already
landed in drm-intel-fixes as:

commit e90f3b61f4432e3c5bb6b57f4b3e8d8cba747541
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Apr 30 19:35:02 2012 +0100

    drm/i915: Only enable IPS polling for gen5

Thanks for the report.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48