[Intel-gfx] [PATCH] Revert "drm/i915: Use atomic commits for legacy page_flips"

[Maarten Lankhorst]

Op 28-06-16 om 10:35 schreef Chris Wilson:
> On Tue, Jun 28, 2016 at 09:56:47AM +0200, Maarten Lankhorst wrote:
>> Op 24-06-16 om 14:44 schreef Chris Wilson:
>>> This reverts commit ee042aa40b66d18d465206845b0752c6a617ba3f.
>>>
>>> Something appears to be off in the timing, but as far as I can tell it
>>> is not along the event delivery path. The net effect appears to be
>>> rendering flicker (the current render buffer appears on the scanout,
>>> with what appears to be active rendering for a fraction of a frame) and
>>> is causing me a headache.
>>>
>>> The cursor is also being stalled by page flips, causing a "heavy mouse"
>>> and jitter.
>>>
>>> Reported-and-tested-by: Steven Newbury <steve at snewbury.org.uk>
>>> Reported-by:  Rafael Ristovski  <rafael.ristovski at gmail.com>
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96593
>>> Testcase: igt/kms_cursor_legacy/basic-flip-vs-cursor
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/intel_display.c | 3 +--
>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>>> index 1141b86..d4a7872 100644
>>> --- a/drivers/gpu/drm/i915/intel_display.c
>>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>> @@ -11646,7 +11646,6 @@ void intel_check_page_flip(struct drm_i915_private *dev_priv, int pipe)
>>>  	spin_unlock(&dev->event_lock);
>>>  }
>>>  
>>> -__maybe_unused
>>>  static int intel_crtc_page_flip(struct drm_crtc *crtc,
>>>  				struct drm_framebuffer *fb,
>>>  				struct drm_pending_vblank_event *event,
>>> @@ -14008,7 +14007,7 @@ static const struct drm_crtc_funcs intel_crtc_funcs = {
>>>  	.set_config = drm_atomic_helper_set_config,
>>>  	.set_property = drm_atomic_helper_crtc_set_property,
>>>  	.destroy = intel_crtc_destroy,
>>> -	.page_flip = drm_atomic_helper_page_flip,
>>> +	.page_flip = intel_crtc_page_flip,
>>>  	.atomic_duplicate_state = intel_crtc_duplicate_state,
>>>  	.atomic_destroy_state = intel_crtc_destroy_state,
>>>  };
>> This still wouldn't fix updates based on nonblocking atomic commits, though probably less likely.
>>
>> Does this bug get fixed by "drm/i915: Don't stall too much for cursor vs. pageflip" ?
> Only one side, cursor still stalls flips (or rather a flip can miss 10s of
> vblanks under load), and the wrong buffers are still visible.
> -Chris
Since this only affects legacy page flips the fix is fine for now till we fix the root cause.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>