linux-kernel - [PATCH 4.9 130/145] [media] tw5864: use dev_warn instead of WARN to shut up warning

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Message-Id: <20180223170741.602094154@linuxfoundation.org>
Date:   Fri, 23 Feb 2018 19:27:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Andrey Utkin <andrey.utkin@...p.bluecherry.net>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>
Subject: [PATCH 4.9 130/145] [media] tw5864: use dev_warn instead of WARN to shut up warning

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit 27430d19a91615245babaa9b216d0807636903a0 upstream.

tw5864_frameinterval_get() only initializes its output when it successfully
identifies the video standard in tw5864_input. We get a warning here because
gcc can't always track the state if initialized warnings across a WARN()
macro, and thinks it might get used incorrectly in tw5864_s_parm:

media/pci/tw5864/tw5864-video.c: In function 'tw5864_s_parm':
media/pci/tw5864/tw5864-video.c:816:38: error: 'time_base.numerator' may be used uninitialized in this function [-Werror=maybe-uninitialized]
media/pci/tw5864/tw5864-video.c:819:31: error: 'time_base.denominator' may be used uninitialized in this function [-Werror=maybe-uninitialized]

Using dev_warn() instead of WARN() avoids the __branch_check__() in
unlikely and lets the compiler see that the initialization is correct.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Andrey Utkin <andrey.utkin@...p.bluecherry.net>
Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/pci/tw5864/tw5864-video.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/media/pci/tw5864/tw5864-video.c
+++ b/drivers/media/pci/tw5864/tw5864-video.c
@@ -708,6 +708,8 @@ static void tw5864_frame_interval_set(st
 static int tw5864_frameinterval_get(struct tw5864_input *input,
 				    struct v4l2_fract *frameinterval)
 {
+	struct tw5864_dev *dev = input->root;
+
 	switch (input->std) {
 	case STD_NTSC:
 		frameinterval->numerator = 1001;
@@ -719,8 +721,8 @@ static int tw5864_frameinterval_get(stru
 		frameinterval->denominator = 25;
 		break;
 	default:
-		WARN(1, "tw5864_frameinterval_get requested for unknown std %d\n",
-		     input->std);
+	        dev_warn(&dev->pci->dev, "tw5864_frameinterval_get requested for unknown std %d\n",
+			 input->std);
 		return -EINVAL;
 	}