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

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

On Thu, Feb 19, 2026 at 05:19:46PM +0100, Michael Riesch wrote:
> On 2/19/26 10:13, Laurent Pinchart wrote:
> > 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 ?
> 
> To keep the two rkcif_stream_pop_buffer calls together. We need to
> allocate the dummy in any case, but in case the second pop fails we use
> it -- this was not the case before.

I suppose it's easier than returning buffers[0] in the dummy buffer
allocate error path. Works for me.

> >> -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().
> 
> Makes sense, will fix.
> 
> >>  }
> >>  

-- 
Regards,

Laurent Pinchart