linux-kernel - [PATCH 2/2] [media] s5p-mfc: don't print errors on VIDIOC

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Message-Id: <1465437455-24110-2-git-send-email-javier@osg.samsung.com>
Date:	Wed,  8 Jun 2016 21:57:35 -0400
From:	Javier Martinez Canillas <javier@....samsung.com>
To:	linux-kernel@...r.kernel.org
Cc:	Luis de Bethencourt <luisbg@....samsung.com>,
	Nicolas Dufresne <nicolas.dufresne@...labora.com>,
	Shuah Khan <shuahkh@....samsung.com>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Kamil Debski <k.debski@...sung.com>,
	Jeongtae Park <jtp.park@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: [PATCH 2/2] [media] s5p-mfc: don't print errors on VIDIOC_REQBUFS unsupported mem type

The V4L2 documentation says that applications must call the VIDIOC_REQBUFS
ioctl to determine if a memory mapped, user pointer or DMABUF based I/O is
supported by the driver.

For example GStreamer does this by first calling VIDIOC_REQBUFS with count
zero for all the possible streaming I/O methods and then finally doing the
real VIDIOC_REQBUFS with count N using a known to be supported memory type.

But the driver prints an error on VIDIOC_REQBUFS if the memory type is not
supported which leads to the following errors that can confuse the users:

[  178.704390] vidioc_reqbufs:575: Only V4L2_MEMORY_MMAP is supported
[  178.704666] vidioc_reqbufs:575: Only V4L2_MEMORY_MMAP is supported
[  178.714956] vidioc_reqbufs:575: Only V4L2_MEMORY_MMAP is supported
[  178.715229] vidioc_reqbufs:575: Only V4L2_MEMORY_MMAP is supported

Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>

---

 drivers/media/platform/s5p-mfc/s5p_mfc_dec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_dec.c b/drivers/media/platform/s5p-mfc/s5p_mfc_dec.c
index 8e2ee1a0df2b..038215c198ac 100644
--- a/drivers/media/platform/s5p-mfc/s5p_mfc_dec.c
+++ b/drivers/media/platform/s5p-mfc/s5p_mfc_dec.c
@@ -572,7 +572,7 @@ static int vidioc_reqbufs(struct file *file, void *priv,
 	struct s5p_mfc_ctx *ctx = fh_to_ctx(priv);
 
 	if (reqbufs->memory != V4L2_MEMORY_MMAP) {
-		mfc_err("Only V4L2_MEMORY_MMAP is supported\n");
+		mfc_debug(2, "Only V4L2_MEMORY_MMAP is supported\n");
 		return -EINVAL;
 	}
 
-- 
2.5.5