Re: [PATCH 2/5] drm/omap: check that plane is inside crtc

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Thursday 18 June 2015 13:10:36 Tomi Valkeinen wrote:
> DRM allows planes to be partially off-screen, but DSS hardware does not.
> This patch adds the necessary check to reject plane configs if the plane
> is not fully inside the crtc.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/omap_plane.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_plane.c
> b/drivers/gpu/drm/omapdrm/omap_plane.c index cfa8276c4deb..53594a3b4e98
> 100644
> --- a/drivers/gpu/drm/omapdrm/omap_plane.c
> +++ b/drivers/gpu/drm/omapdrm/omap_plane.c
> @@ -17,6 +17,7 @@
>   * this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
> 
> +#include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_plane_helper.h>
> 
> @@ -153,9 +154,34 @@ static void omap_plane_atomic_disable(struct drm_plane
> *plane, dispc_ovl_enable(omap_plane->id, false);
>  }
> 
> +static int omap_plane_atomic_check(struct drm_plane *plane,
> +				   struct drm_plane_state *state)
> +{
> +	struct drm_crtc_state *crtc_state;
> +
> +	if (!state->crtc)
> +		return 0;
> +
> +	crtc_state = drm_atomic_get_crtc_state(state->state, state->crtc);
> +	if (!crtc_state)
> +		return 0;

drm_atomic_get_crtc_state() returns an ERR_PTR on error. You should then 
propagate the error to the caller:

	crtc_state = drm_atomic_get_crtc_state(state->state, state->crtc);
	if (IS_ERR(crtc_state))
		return PTR_ERR(crtc_state);

> +	if (state->crtc_x < 0 || state->crtc_y < 0)
> +		return -EINVAL;
> +
> +	if (state->crtc_x + state->crtc_w > crtc_state->adjusted_mode.hdisplay)
> +		return -EINVAL;
> +
> +	if (state->crtc_y + state->crtc_h > crtc_state->adjusted_mode.vdisplay)
> +		return -EINVAL;

I wonder whether we couldn't clip the plane in software instead of failing. 
This patch is fine though (except for the problem above), clipping can be 
implemented in a separate patch.

> +	return 0;
> +}
> +
>  static const struct drm_plane_helper_funcs omap_plane_helper_funcs = {
>  	.prepare_fb = omap_plane_prepare_fb,
>  	.cleanup_fb = omap_plane_cleanup_fb,
> +	.atomic_check = omap_plane_atomic_check,
>  	.atomic_update = omap_plane_atomic_update,
>  	.atomic_disable = omap_plane_atomic_disable,
>  };

-- 
Regards,

Laurent Pinchart

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