On Thu, Jan 12, 2023 at 05:21:45PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> We don't have proper sub-pixel coordinate support (some platforms
> simply can't do it, for others we've not implemented it). This
> can cause us to treat a < 1 pixel source width/height as zero
> which is not valid for the hardware, and can also cause a div
> by zero in some cases.
>
> Refuse < 1x1 plane source size to avoid these problems.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Juha-Pekka Heikkila <juhapekka.heikkila@xxxxxxxxx>
> Reported-by: Drew Davenport <ddavenport@xxxxxxxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> The other option would be to clamp the source size to >=1x1 pixels,
> but dunno if that has any real benefits.
>
> drivers/gpu/drm/i915/display/intel_atomic_plane.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> index 10e1fc9d0698..c6e43d684458 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> @@ -921,6 +921,21 @@ int intel_atomic_plane_check_clipping(struct intel_plane_state *plane_state,
> */
> plane_state->uapi.visible = drm_rect_clip_scaled(src, dst, clip);
>
> + /*
> + * Avoid zero source size when we later
> + * discard the fractional coords.
> + *
> + * FIXME add proper sub-pixel coordinate handling
> + * for platforms/planes that support it.
> + */
> + if (plane_state->uapi.visible &&
> + (drm_rect_width(src) < 0x10000 || drm_rect_height(src) < 0x10000)) {
> + drm_dbg_kms(&i915->drm, "Plane source must be at least 1x1 pixels\n");
> + drm_rect_debug_print("src: ", src, true);
> + drm_rect_debug_print("dst: ", dst, false);
> + return -EINVAL;
> + }
Scratch that. Went with Drew's original patch instead.
> +
> drm_rect_rotate_inv(src, fb->width << 16, fb->height << 16, rotation);
>
> if (!can_position && plane_state->uapi.visible &&
> --
> 2.38.2
--
Ville Syrjälä
Intel
