media: rkvdec: 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 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 <ezequiel@collabora.com>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
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/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
index 8c17615..7131156 100644 (file)
--- 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;
 }