[Intel-gfx] [PATCH] drm/i915/guc: Skip suspend/resume GuC action on platforms w/o GuC submission

[Chris Wilson]

Quoting don.hiatt at intel.com (2019-11-15 23:15:38)
> From: Don Hiatt <don.hiatt at intel.com>
> 
> On some platforms (e.g. KBL) that do not support GuC submission, but
> the user enabled the GuC communication (e.g for HuC authentication)
> calling the GuC EXIT_S_STATE action results in lose of ability to
> enter RC6. We can remove the GuC suspend/resume entirely as we do
> not need to save the GuC submission status.
> 
> Add intel_guc_submission_is_enabled() function to determine if
> GuC submission is active.
> 
> v2: Do not suspend/resume the GuC on platforms that do not support
>     Guc Submission.
> v3: Fix typo, move suspend logic to remove goto.
> v4: Use intel_guc_submission_is_enabled() to check GuC submission
>     status.
> v5: No need to look at engine to determine if submission is enabled.
>     Squash fix + intel_guc_submission_is_enabled() patch into one.
> v6: Move resume check into intel_guc_resume() for symmetry.
>     Fix commit Fixes tag.
> 
> Reported-by: KiteStramuort <kitestramuort at autistici.org>
> Reported-by: S. Zharkoff <s.zharkoff at gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111594
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111623
> Fixes: ffd5ce22faa4 ("drm/i915/guc: Updates for GuC 32.0.3 firmware")
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Daniele Ceralo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Stuart Summers <stuart.summers at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Tested-by: Tomas Janousek <tomi at nomi.cz>
> Signed-off-by: Don Hiatt <don.hiatt at intel.com>

This fixes a rather nasty bug; looks simple enough to be backport
friendly and any further bikesheds can be applied along with guc
refactoring.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris