Re: [PATCH 2/2] media: rockchip: rkcif: comply with minimum number of buffers requirement

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Mon, Feb 16, 2026 at 02:49:57PM +0100, Michael Riesch via B4 Relay wrote:
> From: Michael Riesch <michael.riesch@collabora.com>
> 
> Each stream requires CIF_REQ_BUFS_MIN=1 buffers to enable streaming.
> However, it failed with only one buffer provided.
> 
> Comply with the minimum number of buffers requirement and accept
> exactly one buffer.
> 
> Fixes: 501802e2ad51 ("media: rockchip: rkcif: add abstraction for dma blocks")
> Cc: stable@kernel.org
> Signed-off-by: Michael Riesch <michael.riesch@collabora.com>
> ---
>  .../media/platform/rockchip/rkcif/rkcif-stream.c   | 41 +++++++++++-----------
>  1 file changed, 21 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/media/platform/rockchip/rkcif/rkcif-stream.c b/drivers/media/platform/rockchip/rkcif/rkcif-stream.c
> index e00010a91e8b..5a5ab9e7e86e 100644
> --- a/drivers/media/platform/rockchip/rkcif/rkcif-stream.c
> +++ b/drivers/media/platform/rockchip/rkcif/rkcif-stream.c
> @@ -106,19 +106,6 @@ static int rkcif_stream_init_buffers(struct rkcif_stream *stream)
>  {
>  	struct v4l2_pix_format_mplane *pix = &stream->pix;
>  
> -	stream->buffers[0] = rkcif_stream_pop_buffer(stream);
> -	if (!stream->buffers[0])
> -		goto err_buff_0;
> -
> -	stream->buffers[1] = rkcif_stream_pop_buffer(stream);
> -	if (!stream->buffers[1])
> -		goto err_buff_1;
> -
> -	if (stream->queue_buffer) {
> -		stream->queue_buffer(stream, 0);
> -		stream->queue_buffer(stream, 1);
> -	}
> -
>  	stream->dummy.size = pix->num_planes * pix->plane_fmt[0].sizeimage;
>  	stream->dummy.vaddr =
>  		dma_alloc_attrs(stream->rkcif->dev, stream->dummy.size,
> @@ -132,16 +119,30 @@ static int rkcif_stream_init_buffers(struct rkcif_stream *stream)
>  			stream->dummy.buffer.buff_addr[i - 1] +
>  			pix->plane_fmt[i - 1].bytesperline * pix->height;
>  
> -	return 0;
> +	stream->buffers[0] = rkcif_stream_pop_buffer(stream);
> +	if (!stream->buffers[0])
> +		goto err_buff_0;

Why do you move this after allocation of the dummy buffer, to then add
dma_free_attrs() in the err_buff_0 error path ?

>  
> -err_dummy:
> -	rkcif_stream_return_buffer(stream->buffers[1], VB2_BUF_STATE_QUEUED);
> -	stream->buffers[1] = NULL;
> +	stream->buffers[1] = rkcif_stream_pop_buffer(stream);
> +	if (!stream->buffers[1]) {
> +		stream->buffers[stream->frame_phase] = &stream->dummy.buffer;
> +		stream->buffers[stream->frame_phase]->is_dummy = true;
> +	}
> +
> +	if (stream->queue_buffer) {
> +		stream->queue_buffer(stream, 0);
> +		stream->queue_buffer(stream, 1);
> +	}
> +
> +	return 0;
>  
> -err_buff_1:
> -	rkcif_stream_return_buffer(stream->buffers[0], VB2_BUF_STATE_QUEUED);
> -	stream->buffers[0] = NULL;
>  err_buff_0:
> +	dma_free_attrs(stream->rkcif->dev, stream->dummy.size,
> +		       stream->dummy.vaddr,
> +		       stream->dummy.buffer.buff_addr[0],
> +		       DMA_ATTR_NO_KERNEL_MAPPING);
> +	stream->dummy.vaddr = NULL;
> +err_dummy:
>  	return -EINVAL;

You can drop the err_dummy label and return -EINVAL directly. Except you
should probably return -ENOMEM as the failure comes from
dma_alloc_attrs().

>  }
>  

-- 
Regards,

Laurent Pinchart