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57 lines
2.1 KiB
Diff
57 lines
2.1 KiB
Diff
From c84676e57896fedb47a69739fb82bb9941f624c4 Mon Sep 17 00:00:00 2001
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From: Mariusz Bialonczyk <manio@skyboo.net>
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Date: Wed, 22 May 2019 12:40:53 +0200
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Subject: [PATCH] w1: ds2413: when the slave is not responding during
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read, select it again
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commit 3856032a0628e6b94badb9131a706dda185e071d upstream.
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The protocol is not allowing to obtain a byte of 0xff for PIO_ACCESS_READ
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call. It is very likely that the slave was not addressed properly and
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it is just not respoding (leaving the bus in logic high state) during
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the read of sampled PIO value.
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We cannot just call w1_reset_resume_command() because the problem will
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persist, instead try selecting (addressing) the slave again.
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Signed-off-by: Mariusz Bialonczyk <manio@skyboo.net>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/w1/slaves/w1_ds2413.c | 9 ++++++++-
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1 file changed, 8 insertions(+), 1 deletion(-)
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--- a/drivers/w1/slaves/w1_ds2413.c
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+++ b/drivers/w1/slaves/w1_ds2413.c
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@@ -24,6 +24,7 @@
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#define W1_F3A_FUNC_PIO_ACCESS_READ 0xF5
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#define W1_F3A_FUNC_PIO_ACCESS_WRITE 0x5A
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#define W1_F3A_SUCCESS_CONFIRM_BYTE 0xAA
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+#define W1_F3A_INVALID_PIO_STATE 0xFF
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static ssize_t state_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *buf, loff_t off,
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@@ -45,6 +46,7 @@ static ssize_t state_read(struct file *f
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mutex_lock(&sl->master->bus_mutex);
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dev_dbg(&sl->dev, "mutex locked");
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+next:
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if (w1_reset_select_slave(sl))
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goto out;
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@@ -52,10 +54,15 @@ static ssize_t state_read(struct file *f
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w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
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*buf = w1_read_8(sl->master);
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- /* check for correct complement */
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if ((*buf & 0x0F) == ((~*buf >> 4) & 0x0F)) {
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+ /* complement is correct */
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bytes_read = 1;
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goto out;
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+ } else if (*buf == W1_F3A_INVALID_PIO_STATE) {
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+ /* slave didn't respond, try to select it again */
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+ dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
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+ "reselecting, retries left: %d\n", retries);
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+ goto next;
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}
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if (w1_reset_resume_command(sl->master))
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