[Intel-gfx] [PATCH] drm/i915: Fix waiting for engines to idle

[Tvrtko Ursulin]

On 23/05/2017 11:30, Chris Wilson wrote:
> On Tue, May 23, 2017 at 11:09:17AM +0100, Chris Wilson wrote:
>> On Tue, May 23, 2017 at 10:36:34AM +0100, Chris Wilson wrote:
>>> On Tue, May 23, 2017 at 10:19:31AM +0100, Tvrtko Ursulin wrote:
>>>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>>>
>>>> Waiting for engines needs to happen even in the non-debug builds
>>>> so it is incorrect to wrap it in a GEM_WARN_ON.
>>>>
>>>> Call it unconditionally and add GEM_WARN so that the debug
>>>> warning can still be emitted when things go bad.
>>>>
>>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>>> Fixes: 25112b64b3d2 ("drm/i915: Wait for all engines to be idle as part of i915_gem_wait_for_idle()")
>>>
>>> I would also say
>>> Fixes: 7a453fb82f86 ("drm/i915: Remove redudant wait for each engine to idle from seqno wrap")
>>> as that's the patch that assumes wait_for_idle included the wait on
>>> engines.
>>
>> Hmm, actually that was only to prevent a DEBUG_GEM failure so not a
>> relevant citation for fixes?
>
> And actually, this if for debug only code so the Fixes 25112b64b3d2 is
> wrong as well as we as introducing a change in behaviour (making the
> debug only code run all the time) with no urgent need for backporting.

Which part is for debug code only? Without it i915_gem_wait_for_idle is 
left with no checking for irq idleness, but it only seqno based. If that 
is what you say is debug only I think we need to mark it better in the code.

Regards,

Tvrtko