target/linux/brcm2708/patches-4.19/950-0591-w1-ds2413-fix-state-byte-comparision.patch

   1 From 38ca046063ee6fcef66c9c3bec5844a65f9d48d9 Mon Sep 17 00:00:00 2001
   2 From: Mariusz Bialonczyk <manio@skyboo.net>
   3 Date: Thu, 30 May 2019 09:51:25 +0200
   4 Subject: [PATCH] w1: ds2413: fix state byte comparision
   5
   6 commit aacd152ecd7b18af5d2d96dea9e7284c1c93abea upstream.
   7
   8 This commit is fixing a smatch warning:
   9 drivers/w1/slaves/w1_ds2413.c:61 state_read() warn: impossible condition '(*buf == 255) => ((-128)-127 == 255)'
  10 by creating additional u8 variable for the bus reading and comparision
  11
  12 Reported-by: kbuild test robot <lkp@intel.com>
  13 Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
  14 Cc: Dan Carpenter <dan.carpenter@oracle.com>
  15 Fixes: 3856032a0628 ("w1: ds2413: when the slave is not responding during read, select it again")
  16 Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18 ---
  19  drivers/w1/slaves/w1_ds2413.c | 8 +++++---
  20  1 file changed, 5 insertions(+), 3 deletions(-)
  21
  22 --- a/drivers/w1/slaves/w1_ds2413.c
  23 +++ b/drivers/w1/slaves/w1_ds2413.c
  24 @@ -33,6 +33,7 @@ static ssize_t state_read(struct file *f
  25         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  26         unsigned int retries = W1_F3A_RETRIES;
  27         ssize_t bytes_read = -EIO;
  28 +       u8 state;
  29
  30         dev_dbg(&sl->dev,
  31                 "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
  32 @@ -53,12 +54,13 @@ next:
  33         while (retries--) {
  34                 w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
  35
  36 -               *buf = w1_read_8(sl->master);
  37 -               if ((*buf & 0x0F) == ((~*buf >> 4) & 0x0F)) {
  38 +               state = w1_read_8(sl->master);
  39 +               if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
  40                         /* complement is correct */
  41 +                       *buf = state;
  42                         bytes_read = 1;
  43                         goto out;
  44 -               } else if (*buf == W1_F3A_INVALID_PIO_STATE) {
  45 +               } else if (state == W1_F3A_INVALID_PIO_STATE) {
  46                         /* slave didn't respond, try to select it again */
  47                         dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
  48                                             "reselecting, retries left: %d\n", retries);