[Intel-gfx] [PATCH] drm/i915: Do not check or a stalled pageflip prior to it being queued

[Ville Syrjälä]

On Wed, Aug 12, 2015 at 01:08:22PM +0100, Chris Wilson wrote:
> When we queue the command or operation to change the scanout address, we
> mark the flip as in progress. We can use this flag to prevent us from
> checking for a stalled flip prior to its existence!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  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 aab8dfd1f8a5..edc7d4a7c9de 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11248,6 +11248,9 @@ static bool __intel_pageflip_stall_check(struct drm_device *dev,
>  	if (atomic_read(&work->pending) >= INTEL_FLIP_COMPLETE)
>  		return true;
>  
> +	if (atomic_read(&work->pending) < INTEL_FLIP_PENDING)
> +		return false;
> +

unpin_work is assigned and the lock dropped before the flip is marked as
INTEL_FLIP_PENDING. Makes sense.

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

>  	if (!work->enable_stall_check)
>  		return false;
>  
> -- 
> 2.5.0
> 
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-- 
Ville Syrjälä
Intel OTC