From: Ezequiel Garcia <redacted>

[ Upstream commit ba1ed4ae760a81caf39f54232e089d95157a0dba ]

The driver should only set the payload on .buf_prepare if the
buffer is CAPTURE type. If an OUTPUT buffer has a zero bytesused
set by userspace then v4l2-core will set it to buffer length.

If we overwrite bytesused for OUTPUT buffers, too, then
vb2_get_plane_payload() will return incorrect value which might be then
written to hw registers by the driver in rkvdec-h264.c.

[Changed the comment and used V4L2_TYPE_IS_CAPTURE macro]

Fixes: cd33c830448ba ("media: rkvdec: Add the rkvdec driver")
Signed-off-by: Ezequiel Garcia <redacted>
Signed-off-by: Adrian Ratiu <redacted>
Signed-off-by: Andrzej Pietrasiewicz <redacted>
Signed-off-by: Hans Verkuil <redacted>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/staging/media/rkvdec/rkvdec.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
index 8c17615f3a7a..7131156c1f2c 100644
--- a/drivers/staging/media/rkvdec/rkvdec.c
+++ b/drivers/staging/media/rkvdec/rkvdec.c

@@ -481,7 +481,15 @@ static int rkvdec_buf_prepare(struct vb2_buffer *vb)
 		if (vb2_plane_size(vb, i) < sizeimage)
 			return -EINVAL;
 	}
-	vb2_set_plane_payload(vb, 0, f->fmt.pix_mp.plane_fmt[0].sizeimage);
+
+	/*
+	 * Buffer's bytesused must be written by driver for CAPTURE buffers.
+	 * (for OUTPUT buffers, if userspace passes 0 bytesused, v4l2-core sets
+	 * it to buffer length).
+	 */
+	if (V4L2_TYPE_IS_CAPTURE(vq->type))
+		vb2_set_plane_payload(vb, 0, f->fmt.pix_mp.plane_fmt[0].sizeimage);
+
 	return 0;
 }
 

-- 
2.30.2