-----Original Message-----
From: linux-arm-kernel-bounces at lists.infradead.org [mailto:linux-arm-
kernel-bounces at lists.infradead.org] On Behalf Of Wolfram Sang
Sent: Thursday, November 24, 2011 4:38 PM
To: Uwe Kleine-K?nig
Cc: Shawn Guo; linux-arm-kernel at lists.infradead.org; Ben Dooks; linux-
i2c at vger.kernel.org
Subject: Re: [PATCH] i2c-mxs: fix compile warning in mxs_i2c_xfer()

On Thu, Nov 24, 2011 at 09:29:03AM +0100, Uwe Kleine-K?nig wrote:

quoted

Hello Shawn,

On Thu, Nov 24, 2011 at 03:52:20PM +0800, Shawn Guo wrote:

quoted

  CC      drivers/i2c/busses/i2c-mxs.o
drivers/i2c/busses/i2c-mxs.c: In function ?mxs_i2c_xfer?:
drivers/i2c/busses/i2c-mxs.c:196:6: warning: ?data? may be used
uninitialized in this function

Signed-off-by: Shawn Guo <redacted>
---
 drivers/i2c/busses/i2c-mxs.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mxs.c

b/drivers/i2c/busses/i2c-mxs.c index 7e78f7c..00f098f 100644

--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c

@@ -193,7 +193,7 @@ static int mxs_i2c_wait_for_data(struct

mxs_i2c_dev *i2c)

 static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf,
int len)  {
-	u32 data;
+	u32 data = 0;
 	int i;

 	for (i = 0; i < len; i++) {

Looks like a stupid compiler. Then better use

	u32 uninitialized_var(data);

Leave it as it is and fix the compiler? Will do another test later to
make sure.

Compiler is wrong?
Just from the code that it seems to be right the 'data' might be used
uninitialized.

Something I missed?

static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
{
        u32 data;
        int i;

        for (i = 0; i < len; i++) {
                if ((i & 3) == 0) {
                        if (mxs_i2c_wait_for_data(i2c))
                                return -ETIMEDOUT;
                        data = readl(i2c->regs + MXS_I2C_QUEUEDATA);
                }
                buf[i] = data & 0xff;
                data >>= 8;
        }

        return 0;
}

Regards
Dong Aisheng