1 From 91e443597cdd8f89d2b68ea5bf0f0823d1853ab7 Mon Sep 17 00:00:00 2001
2 From: Mariusz Bialonczyk <manio@skyboo.net>
3 Date: Mon, 20 May 2019 09:05:56 +0200
4 Subject: [PATCH] w1: ds2413: add retry support to state_read()
6 commit c50d09a86172073f55ebac0b92ad5a75907d64e7 upstream.
8 The state_read() was calling PIO_ACCESS_READ once and bail out if it
9 failed for this first time.
10 This commit is improving this to trying more times before it give up,
11 similarly as the write call is currently doing.
13 Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
14 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
16 drivers/w1/slaves/w1_ds2413.c | 37 +++++++++++++++++++++++------------
17 1 file changed, 24 insertions(+), 13 deletions(-)
19 --- a/drivers/w1/slaves/w1_ds2413.c
20 +++ b/drivers/w1/slaves/w1_ds2413.c
21 @@ -30,6 +30,9 @@ static ssize_t state_read(struct file *f
24 struct w1_slave *sl = kobj_to_w1_slave(kobj);
25 + unsigned int retries = W1_F3A_RETRIES;
26 + ssize_t bytes_read = -EIO;
29 "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
30 bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
31 @@ -42,22 +45,30 @@ static ssize_t state_read(struct file *f
32 mutex_lock(&sl->master->bus_mutex);
33 dev_dbg(&sl->dev, "mutex locked");
35 - if (w1_reset_select_slave(sl)) {
36 - mutex_unlock(&sl->master->bus_mutex);
39 + if (w1_reset_select_slave(sl))
42 - w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
43 - *buf = w1_read_8(sl->master);
45 + w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
47 - mutex_unlock(&sl->master->bus_mutex);
48 - dev_dbg(&sl->dev, "mutex unlocked");
49 + *buf = w1_read_8(sl->master);
50 + /* check for correct complement */
51 + if ((*buf & 0x0F) == ((~*buf >> 4) & 0x0F)) {
56 + if (w1_reset_resume_command(sl->master))
57 + goto out; /* unrecoverable error */
59 - /* check for correct complement */
60 - if ((*buf & 0x0F) != ((~*buf >> 4) & 0x0F))
64 + dev_warn(&sl->dev, "PIO_ACCESS_READ error, retries left: %d\n", retries);
68 + mutex_unlock(&sl->master->bus_mutex);
69 + dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
70 + (bytes_read > 0) ? "succeeded" : "error", retries);
74 static BIN_ATTR_RO(state, 1);