On Thu, Jan 12, 2023 at 05:21:45PM +0200, Ville Syrjala wrote:

From: Ville Syrjälä ville.syrjala@linux.intel.com

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@vger.kernel.org Cc: Juha-Pekka Heikkila juhapekka.heikkila@gmail.com Reported-by: Drew Davenport ddavenport@chromium.org Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com

---

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