linux-kernel - [PATCH v2 4/4] vb2: V4L2_BUF_FLAG

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Date:	Mon, 20 Jun 2016 14:30:09 +0200
From:	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
To:	Pawel Osciak <pawel@...iak.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	hans.verkuil@...co.com, hverkuil@...all.nl
Cc:	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Subject: [PATCH v2 4/4] vb2: V4L2_BUF_FLAG_DONE is set after DQBUF

According to the doc, V4L2_BUF_FLAG_DONE is cleared after DQBUF:

V4L2_BUF_FLAG_DONE 0x00000004  ... After calling the VIDIOC_QBUF or
VIDIOC_DQBUF it is always cleared ...

Unfortunately, it seems that videobuf2 keeps it set after DQBUF. This
can be tested with vivid and dev_debug:

[257604.338082] video1: VIDIOC_DQBUF: 71:33:25.00260479 index=3,
type=vid-cap, flags=0x00002004, field=none, sequence=163,
memory=userptr, bytesused=460800, offset/userptr=0x344b000,
length=460800

This patch forces FLAG_DONE to 0 after calling DQBUF.

Reported-by: Dimitrios Katsaros <patcherwork@...il.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
---
 drivers/media/v4l2-core/videobuf2-v4l2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
index ba3467468e55..9cfbb6e4bc28 100644
--- a/drivers/media/v4l2-core/videobuf2-v4l2.c
+++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
@@ -654,6 +654,12 @@ int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
 
 	ret = vb2_core_dqbuf(q, NULL, b, nonblocking);
 
+	/*
+	 *  After calling the VIDIOC_DQBUF V4L2_BUF_FLAG_DONE must be
+	 *  cleared.
+	 */
+	b->flags &= ~V4L2_BUF_FLAG_DONE;
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vb2_dqbuf);
-- 
2.8.1