On Thu, Nov 12, 2015 at 11:11:20AM -0200, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> 
> Fixes an regression added by 3ae2436 (drm/exynos/mixer: replace
> direct cross-driver call with drm mode). The whole atomic update
> was failing if the hdmi display is not present/active. Add a test
> to only run atomic_check() if the CRTC is active.
> 
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> index b3ba27f..1d3ca0a 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> @@ -55,6 +55,9 @@ static int exynos_crtc_atomic_check(struct drm_crtc *crtc,
>  {
>  	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
>  
> +	if (!state->active)
> +		return 0;
> +
>  	if (exynos_crtc->ops->atomic_check)
>  		return exynos_crtc->ops->atomic_check(exynos_crtc, state);
>  

This looks like something that the core should be doing.

Thierry