media: cedrus: Fix .buf_prepare

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 cedrus_h264.c or cedrus_vp8.c.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
index 9ddd789..32c13ec 100644 (file)
--- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
@@ -457,7 +457,13 @@ static int cedrus_buf_prepare(struct vb2_buffer *vb)
        if (vb2_plane_size(vb, 0) < pix_fmt->sizeimage)
                return -EINVAL;
 
-       vb2_set_plane_payload(vb, 0, pix_fmt->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, pix_fmt->sizeimage);
 
        return 0;
 }