[PATCH] media: rkvdec: Fix .buf_prepare

[Andrzej Pietrasiewicz]

From: Ezequiel Garcia <ezequiel at collabora.com>

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.

Fixes: cd33c830448ba ("media: rkvdec: Add the rkvdec driver")
Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
Signed-off-by: Adrian Ratiu <adrian.ratiu at collabora.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at collabora.com>

---
@Hans: I haven't had anyone complain about the issue. The fix is needed for
the rkvdec vp9 work, so I think 5.14 is fine.

 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 d821661d30f3..ef2166043127 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 bytesused is written by driver for CAPTURE buffers.
+	 * (if userspace passes 0 bytesused for OUTPUT buffers, v4l2-core sets
+	 * it to buffer length).
+	 */
+	if (!V4L2_TYPE_IS_OUTPUT(vq->type))
+		vb2_set_plane_payload(vb, 0, f->fmt.pix_mp.plane_fmt[0].sizeimage);
+
 	return 0;
 }
 

base-commit: 0b276e470a4d43e1365d3eb53c608a3d208cabd4
-- 
2.17.1