[PATCH] media: ov7670: check status of ov7670_read

From: trix@redhat.com
To: corbet@lwn.net, mchehab@kernel.org, natechancellor@gmail.com,
	ndesaulniers@google.com
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
	Tom Rix <trix@redhat.com>
Subject: [PATCH] media: ov7670: check status of ov7670_read
Date: Fri, 28 Aug 2020 07:55:18 -0700	[thread overview]
Message-ID: <20200828145518.26324-1-trix@redhat.com> (raw)

From: Tom Rix <trix@redhat.com>

clang static analysis flags this representative problem

drivers/media/i2c/ov7670.c:1463:9: warning: Assigned
  value is garbage or undefined
        *value = gain;
               ^ ~~~~

gain is set by a successful call to ov7670_read()

So check that ov7670_read() is successful.

The remaining static analysis problems are false positives.
There appears to be a limitation with checking the
aggregated returns.

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/media/i2c/ov7670.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
index b42b289faaef..001d4b09db72 100644
--- a/drivers/media/i2c/ov7670.c
+++ b/drivers/media/i2c/ov7670.c
@@ -929,6 +929,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
 	ret =  ov7670_write(sd, REG_HSTART, (hstart >> 3) & 0xff);
 	ret += ov7670_write(sd, REG_HSTOP, (hstop >> 3) & 0xff);
 	ret += ov7670_read(sd, REG_HREF, &v);
+	if (ret)
+		return ret;
 	v = (v & 0xc0) | ((hstop & 0x7) << 3) | (hstart & 0x7);
 	msleep(10);
 	ret += ov7670_write(sd, REG_HREF, v);
@@ -938,6 +940,8 @@ static int ov7670_set_hw(struct v4l2_subdev *sd, int hstart, int hstop,
 	ret += ov7670_write(sd, REG_VSTART, (vstart >> 2) & 0xff);
 	ret += ov7670_write(sd, REG_VSTOP, (vstop >> 2) & 0xff);
 	ret += ov7670_read(sd, REG_VREF, &v);
+	if (ret)
+		return ret;
 	v = (v & 0xf0) | ((vstop & 0x3) << 2) | (vstart & 0x3);
 	msleep(10);
 	ret += ov7670_write(sd, REG_VREF, v);
@@ -1460,6 +1464,8 @@ static int ov7670_g_gain(struct v4l2_subdev *sd, __s32 *value)
 	unsigned char gain;
 
 	ret = ov7670_read(sd, REG_GAIN, &gain);
+	if (ret)
+		return ret;
 	*value = gain;
 	return ret;
 }
@@ -1470,11 +1476,14 @@ static int ov7670_s_gain(struct v4l2_subdev *sd, int value)
 	unsigned char com8;
 
 	ret = ov7670_write(sd, REG_GAIN, value & 0xff);
+	if (ret)
+		return ret;
 	/* Have to turn off AGC as well */
-	if (ret == 0) {
-		ret = ov7670_read(sd, REG_COM8, &com8);
-		ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
-	}
+	ret = ov7670_read(sd, REG_COM8, &com8);
+	if (ret)
+		return ret;
+	ret = ov7670_write(sd, REG_COM8, com8 & ~COM8_AGC);
+
 	return ret;
 }
 
-- 
2.18.1

