Re: [PATCH 3/4] drm/exynos: enable vblank after DPMS on

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Oct 10, 2014 at 02:31:55PM +0200, Andrzej Hajda wrote:
> Before DPMS off driver disables vblank.
> It should be balanced by vblank enable after DPMS on.
> The patch fixes issue with page_flip ioctl not being able
> to acquire vblank counter introduced by patch:
> drm: Always reject drm_vblank_get() after drm_vblank_off()
> 
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>

Yeah, you should always call vblank_on again when you (re)enable a crtc,
whether this is through a set_config call or through dpms. This is
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Sorry that we didn't catch the impact of this additional check on existing
drivers, I've thought I've reviewed them and checked that they all call
vblank_on. But I didn't take into account that the codepaths might differ
for dpms and set_config paths. Otoh most drivers really should implement
one in terms of the other.

Cheers, Daniel

> ---
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> index 8e38e9f..45026e6 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> @@ -71,13 +71,16 @@ static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
>  				!atomic_read(&exynos_crtc->pending_flip),
>  				HZ/20))
>  			atomic_set(&exynos_crtc->pending_flip, 0);
> -		drm_vblank_off(crtc->dev, exynos_crtc->pipe);
> +		drm_crtc_vblank_off(crtc);
>  	}
>  
>  	if (manager->ops->dpms)
>  		manager->ops->dpms(manager, mode);
>  
>  	exynos_crtc->dpms = mode;
> +
> +	if (mode == DRM_MODE_DPMS_ON)
> +		drm_crtc_vblank_on(crtc);
>  }
>  
>  static void exynos_drm_crtc_prepare(struct drm_crtc *crtc)
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch