[PATCH] drm/atomic: Call ww_acquire_done after check phase is complete

Maarten Lankhorst maarten.lankhorst at linux.intel.com
Wed Aug 5 11:13:05 PDT 2015

Op 05-08-15 om 17:03 schreef Daniel Vetter:
> On Wed, Aug 5, 2015 at 4:57 PM, Maarten Lankhorst
> <maarten.lankhorst at linux.intel.com> wrote:
>> Op 05-08-15 om 15:08 schreef Daniel Vetter:
>>> We want to make sure that no one tries to acquire more locks and
>>> states, and ww mutexes provide debug facilities for that. So use them.
>>> Cc: Rob Clark <robdclark at gmail.com>
>>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>>> ---
>>>  drivers/gpu/drm/drm_atomic.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>> I like the idea, played with the thought myself, but I think it might need to be slightly less strict for transitional drivers.
> What would blow up? This should only be called fairly late in the
> transition when most of the atomic handling is correctly done. And
> i915 is probably the most extreme example of a conversion, so if it
> works out for us I think everyone else should be fine too.
Might blow up with transitional helpers, though not 100% sure if it would.

Also if atomic_check returns -EDEADLK you would still say acquire_done, that will definitely blow up in legitimate cases..

If it doesn't blow up transitional helpers and you fix the -EDEADLK, acked-by. :-)
> Generally drivers only started to do fancy stuff with get_*_state once
> converted to atomic to start exploiting it, not before the transition
> is completed. i915 is different since we have a lot of our own modeset
Should we electrify drm_atomic_get_{*}_state too, to force everyone to use the get_existing_state versions?


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