Re: [PATCH] media: meson: vdec: size capture planes from the aligned canvas

[Dan Carpenter]

On Mon, Sep 28, 2026 at 07:50:45PM +0300, Michael Freidkin wrote:
> The decoder writes a whole canvas of ALIGN(width, 32) x ALIGN(height, 32)
> (amvdec_set_canvases()) and reports bytesperline = ALIGN(width, 32), but
> get_output_size() derives sizeimage from the raw width x height.
> 
> When the width is not a multiple of 32 the planes are too small for the
> advertised stride: for 720x360 NV12M the luma plane is 262144 bytes while
> 736 * 360 = 264960 are needed (282624 for the canvas the firmware fills).
> The decoder writes past the buffer, and importing the capture dma-buf
> into DRM fails: drmModeAddFB2() returns -EINVAL, so e.g. Kodi plays the
> sound over a black screen. 1280x720 and 1920x1080 are not affected.
> 
> Size the planes from the aligned canvas the hardware actually uses.
> 
> Tested on an S905X (GXL p212) board with LibreELEC 12 (6.16.0-rc3):
> 720x360 and 1920x1080 H.264 play through V4L2 m2m + DRM PRIME with no
> AddFB2 errors.
> 
> Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
> Signed-off-by: Michael Freidkin <freidkin@xxxxxxxxx>

Reviewed-by: Dan Carpenter <error27@xxxxxxxxx>

It would probably be more reliable to just ALIGN() the width and
height at the start so we don't have to do it over and over again.

regards,
dan carpenter