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w1: ds2413: fix state byte comparision 

This commit is fixing a smatch warning:
drivers/w1/slaves/w1_ds2413.c:61 state_read() warn: impossible condition '(*buf == 255) => ((-128)-127 == 255)'
by creating additional u8 variable for the bus reading and comparision

Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3856032a06 ("w1: ds2413: when the slave is not responding during read, select it again")
Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mariusz Bialonczyk 2019-05-30 09:51:25 +02:00 committed by Greg Kroah-Hartman
parent 7e706da35a
commit aacd152ecd
1 changed files with 5 additions and 3 deletions
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8
drivers/w1/slaves/w1_ds2413.c
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@ -33,6 +33,7 @@ static ssize_t state_read(struct file *filp, struct kobject *kobj,
struct w1_slave *sl = kobj_to_w1_slave(kobj);
unsigned int retries = W1_F3A_RETRIES;
ssize_t bytes_read = -EIO;
u8 state;
dev_dbg(&sl->dev,
"Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
@ -53,12 +54,13 @@ next:
while (retries--) {
w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
*buf = w1_read_8(sl->master);
if ((*buf & 0x0F) == ((~*buf >> 4) & 0x0F)) {
state = w1_read_8(sl->master);
if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
/* complement is correct */
*buf = state;
bytes_read = 1;
goto out;
} else if (*buf == W1_F3A_INVALID_PIO_STATE) {
} else if (state == W1_F3A_INVALID_PIO_STATE) {
/* slave didn't respond, try to select it again */
dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
"reselecting, retries left: %d\n", retries);