[PATCH] drm: move check for min/max width/height for atomic drivers

[Rob Clark]

On Wed, Nov 2, 2016 at 10:27 AM, Rob Clark <robdclark at gmail.com> wrote:
> drm-hwc + android tries to create an fb for the wallpaper layer, which
> is larger than the screen resolution, and potentially larger than
> mode_config->max_{width,height}.  But the plane src_w/src_h is within
> the max limits, so it is something the hardware can otherwise do.
>
> For atomic drivers, defer the check to drm_atomic_plane_check().
>
> Signed-off-by: Rob Clark <robdclark at gmail.com>
> ---
>  drivers/gpu/drm/drm_atomic.c | 17 +++++++++++++++++
>  drivers/gpu/drm/drm_crtc.c   | 26 +++++++++++++++++---------
>  2 files changed, 34 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 34edd4f..fb0f07ce 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -846,7 +846,9 @@ plane_switching_crtc(struct drm_atomic_state *state,
>  static int drm_atomic_plane_check(struct drm_plane *plane,
>                 struct drm_plane_state *state)
>  {
> +       struct drm_mode_config *config = &plane->dev->mode_config;
>         unsigned int fb_width, fb_height;
> +       unsigned int min_width, max_width, min_height, max_height;
>         int ret;
>
>         /* either *both* CRTC and FB must be set, or neither */
> @@ -909,6 +911,21 @@ static int drm_atomic_plane_check(struct drm_plane *plane,
>                 return -ENOSPC;
>         }
>
> +       min_width = config->min_width << 16;
> +       max_width = config->max_width << 16;
> +       min_height = config->min_height << 16;
> +       max_height = config->max_height << 16;
> +
> +       /* Make sure source dimensions are within bounds. */
> +       if (min_width > state->src_w || state->src_w > max_width ||
> +           min_height > state->src_h || state->src_h > max_height) {
> +               DRM_DEBUG_ATOMIC("Invalid source size "
> +                                "%u.%06ux%u.%06u\n",
> +                                state->src_w >> 16, ((state->src_w & 0xffff) * 15625) >> 10,
> +                                state->src_h >> 16, ((state->src_h & 0xffff) * 15625) >> 10);
> +               return -ERANGE;
> +       }
> +
>         if (plane_switching_crtc(state->state, plane, state)) {
>                 DRM_DEBUG_ATOMIC("[PLANE:%d:%s] switching CRTC directly\n",
>                                  plane->base.id, plane->name);
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index b4b973f..7294bde 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -3369,15 +3369,23 @@ internal_framebuffer_create(struct drm_device *dev,
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       if ((config->min_width > r->width) || (r->width > config->max_width)) {
> -               DRM_DEBUG_KMS("bad framebuffer width %d, should be >= %d && <= %d\n",
> -                         r->width, config->min_width, config->max_width);
> -               return ERR_PTR(-EINVAL);
> -       }
> -       if ((config->min_height > r->height) || (r->height > config->max_height)) {
> -               DRM_DEBUG_KMS("bad framebuffer height %d, should be >= %d && <= %d\n",
> -                         r->height, config->min_height, config->max_height);
> -               return ERR_PTR(-EINVAL);
> +       /* for atomic drivers, we check the src dimensions in
> +        * drm_atomic_plane_check().. allow creation of a fb
> +        * that is larger than what can be scanned out, as
> +        * long as userspace doesn't try to scanout a portion
> +        * of the fb that is too large.
> +        */
> +       if (!file_priv->atomic) {

btw, possibly we should loosen this restriction to just DRIVER_ATOMIC?
 It is a problem w/ x11 and multiple screens as well.

BR,
-R

> +               if ((config->min_width > r->width) || (r->width > config->max_width)) {
> +                       DRM_DEBUG_KMS("bad framebuffer width %d, should be >= %d && <= %d\n",
> +                                 r->width, config->min_width, config->max_width);
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               if ((config->min_height > r->height) || (r->height > config->max_height)) {
> +                       DRM_DEBUG_KMS("bad framebuffer height %d, should be >= %d && <= %d\n",
> +                                 r->height, config->min_height, config->max_height);
> +                       return ERR_PTR(-EINVAL);
> +               }
>         }
>
>         if (r->flags & DRM_MODE_FB_MODIFIERS &&
> --
> 2.7.4
>