[Intel-gfx] [PATCH] drm/i915: Avoid stalling on pending flips for legacy cursor updates

[Maarten Lankhorst]

Op 17-04-16 om 21:42 schreef Chris Wilson:
> The legacy cursor ioctl expects to be asynchronous with respect to other
> screen updates, in particular page flips. As X updates the cursor from a
> signal context, if the cursor blocks then it will stall both the input
> and output chains causing bad stuttering and horrible UX.
>
> Reported-and-tested-by: Rafael Ristovski <rafael.ristovski at gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94980
> Fixes: 5008e874edd34 ("drm/i915: Make wait_for_flips interruptible.")
> Suggested-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: stable at vger.kernel.org
> ---
>  drivers/gpu/drm/i915/intel_display.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 4cca155376be..c5b9687091f4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -13446,6 +13446,9 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
>  	}
>  
>  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> +		if (state->legacy_cursor_update)
> +			continue;
> +
>  		ret = intel_crtc_wait_for_pending_flips(crtc);
>  		if (ret)
>  			return ret;
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>