Re: [PATCH 5/9] drm: Have the vblank counter account for the time between vblank irq disable and drm_vblank_off()

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, May 26, 2014 at 02:46:28PM +0300, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> If the vblank irq has already been disabled (via the disable timer) when
> we call drm_vblank_off() sample the counter and timestamp one last time.
> This will make the sure that the user space visible counter will account
> for time between vblank irq disable and drm_vblank_off().
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/drm_irq.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index e12cf69..bb64f0f 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -140,6 +140,19 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc)
>  	 */
>  	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
>  
> +	/*
> +	 * If the vblank interrupt was already disbled update the count
> +	 * and timestamp to maintain the appearance that the counter
> +	 * has been ticking all along until this time. This makes the
> +	 * count account for the entire time between drm_vblank_on() and
> +	 * drm_vblank_off().
> +	 */
> +	if (!dev->vblank[crtc].enabled) {
> +		drm_update_vblank_count(dev, crtc);
> +		spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
> +		return;
> +	}
> +
>  	dev->driver->disable_vblank(dev, crtc);
>  	dev->vblank[crtc].enabled = false;
>  
> -- 
> 1.8.5.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch