Re: [PATCH v2 1/9] drm/rockchip: vop2: Take the UV plane address from the second GEM object

[Chaoyi Chen <chaoyi.chen@rock-chips.com>]

Hi Arun, 

On 11/12/2026 4:33 PM, Arun Iyengar via B4 Relay wrote:
> From: Arun Iyengar <aiyengar1990@gmail.com>
> 
> vop2_plane_atomic_update() computes the address of the chroma plane of a
> multi-planar YUV framebuffer from fb->obj[0], the object of the luma
> plane, plus the offset of the chroma plane. A framebuffer may have its
> planes in different GEM objects though (DRM_IOCTL_MODE_ADDFB2 with two
> handles, as with an NV12M buffer from a V4L2 decoder imported as two
> DMA-BUFs). The window then fetches the chroma plane from the luma buffer,
> at an offset meant for another buffer, which shows a wrong picture or
> reads past the end of the luma buffer.
> 
> Use fb->obj[1] for the chroma plane. Single plane YUV formats like
> DRM_FORMAT_YUV420_8BIT have no second object and keep using fb->obj[0].
> This is also what the vendor kernel does.
> 
> Fixes: 604be85547ce ("drm/rockchip: Add VOP2 driver")
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Closes: https://lore.kernel.org/all/sashiko-outbox-206550@kernel.org/
> Cc: stable@vger.kernel.org
> Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index 76d151b8bc52..ea8d837d661f 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -1369,7 +1369,9 @@ static void vop2_plane_atomic_update(struct drm_plane *plane,
>  		if ((pstate->rotation & DRM_MODE_REFLECT_Y) && !afbc_en)
>  			offset += fb->pitches[1] * ((pstate->src_h >> 16) - 2) / vsub;
>  
> -		rk_obj = to_rockchip_obj(fb->obj[0]);
> +		/* Single plane formats like YUV420_8BIT have no second object */

Drop this comment.


> +		if (fb->format->num_planes > 1)
> +			rk_obj = to_rockchip_obj(fb->obj[1]);
>  		uv_mst = rk_obj->dma_addr + offset + fb->offsets[1];
>  	}
>  
> 

-- 
Best, 
Chaoyi