[PATCH v2] media: m2m-deinterlace: fix default capture field

[raoxu]

From: Xu Rao <raoxu@xxxxxxxxxxxxx>

queue_init() initializes default formats for both the source and capture
queues.  It first sets the source field to V4L2_FIELD_SEQ_TB, but then
stores the capture default, V4L2_FIELD_INTERLACED_TB, in the source queue
again while initializing the capture queue.

This overwrites the valid source default and leaves the capture field at
its zero-initialized value, V4L2_FIELD_ANY.  vidioc_streamon() accepts
only V4L2_FIELD_SEQ_TB or V4L2_FIELD_SEQ_BT on the source queue, and
requires the capture queue to use a compatible interlaced or NONE field.
Userspace that relies on the default formats can therefore get -EINVAL
when starting streaming.

Initialize the capture field instead.  The bug is usually hidden because
mem2mem applications commonly call S_FMT on both queues before streaming;
the TRY_FMT paths normalize the fields and S_FMT overwrites q_data[].field.

Fixes: 8f0755c06b90 ("[media] media: Add mem2mem deinterlacing driver")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>
---
Changes in v2:
- Add Cc: stable@xxxxxxxxxxxxxxx as suggested by Jacopo.
- Add Reviewed-by tag from Jacopo Mondi.

 drivers/media/platform/m2m-deinterlace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/m2m-deinterlace.c b/drivers/media/platform/m2m-deinterlace.c
index 1d0e70eaea3d..9dcc4bd6cbdd 100644
--- a/drivers/media/platform/m2m-deinterlace.c
+++ b/drivers/media/platform/m2m-deinterlace.c
@@ -822,7 +822,7 @@ static int queue_init(void *priv, struct vb2_queue *src_vq,
 	q_data[V4L2_M2M_DST].width = 640;
 	q_data[V4L2_M2M_DST].height = 480;
 	q_data[V4L2_M2M_DST].sizeimage = (640 * 480 * 3) / 2;
-	q_data[V4L2_M2M_SRC].field = V4L2_FIELD_INTERLACED_TB;
+	q_data[V4L2_M2M_DST].field = V4L2_FIELD_INTERLACED_TB;

 	return vb2_queue_init(dst_vq);
 }
--
2.50.1