+++ /dev/null
-From 714580d7c11f81afb5e08c71f79a03a1ed4ae44e Mon Sep 17 00:00:00 2001
-From: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
-Date: Thu, 28 Mar 2019 12:41:11 -0400
-Subject: [PATCH] w1: ds2408: reset on output_write retry with readback
-
-commit 49695ac46861180baf2b2b92c62da8619b6bf28f upstream.
-
-When we have success in 'Channel Access Write' but reading back latch
-states fails, a write is retried without doing a proper slave reset.
-This leads to protocol errors as the slave treats the next 'Channel
-Access Write' as the continuation of previous command.
-
-This commit is fixing this by making sure if the retry loop re-runs, a
-reset is performed, whatever the failure (CONFIRM_BYTE or the read
-back).
-
-The loop was quite due for a cleanup and this change mandated it. By
-isolating the CONFIG_W1_SLAVE_DS2408_READBACK case into it's own
-function, we vastly reduce the visual and branching(runtime and
-compile-time) noise.
-
-Reported-by: Mariusz Bialonczyk <manio@skyboo.net>
-Tested-by: Mariusz Bialonczyk <manio@skyboo.net>
-Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- drivers/w1/slaves/w1_ds2408.c | 76 ++++++++++++++++++-----------------
- 1 file changed, 39 insertions(+), 37 deletions(-)
-
---- a/drivers/w1/slaves/w1_ds2408.c
-+++ b/drivers/w1/slaves/w1_ds2408.c
-@@ -138,14 +138,37 @@ static ssize_t status_control_read(struc
- W1_F29_REG_CONTROL_AND_STATUS, buf);
- }
-
-+#ifdef fCONFIG_W1_SLAVE_DS2408_READBACK
-+static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
-+{
-+ u8 w1_buf[3];
-+
-+ if (w1_reset_resume_command(sl->master))
-+ return false;
-+
-+ w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
-+ w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
-+ w1_buf[2] = 0;
-+
-+ w1_write_block(sl->master, w1_buf, 3);
-+
-+ return (w1_read_8(sl->master) == expected);
-+}
-+#else
-+static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
-+{
-+ return true;
-+}
-+#endif
-+
- static ssize_t output_write(struct file *filp, struct kobject *kobj,
- struct bin_attribute *bin_attr, char *buf,
- loff_t off, size_t count)
- {
- struct w1_slave *sl = kobj_to_w1_slave(kobj);
- u8 w1_buf[3];
-- u8 readBack;
- unsigned int retries = W1_F29_RETRIES;
-+ ssize_t bytes_written = -EIO;
-
- if (count != 1 || off != 0)
- return -EFAULT;
-@@ -155,54 +178,33 @@ static ssize_t output_write(struct file
- dev_dbg(&sl->dev, "mutex locked");
-
- if (w1_reset_select_slave(sl))
-- goto error;
-+ goto out;
-
-- while (retries--) {
-+ do {
- w1_buf[0] = W1_F29_FUNC_CHANN_ACCESS_WRITE;
- w1_buf[1] = *buf;
- w1_buf[2] = ~(*buf);
-- w1_write_block(sl->master, w1_buf, 3);
-
-- readBack = w1_read_8(sl->master);
-+ w1_write_block(sl->master, w1_buf, 3);
-
-- if (readBack != W1_F29_SUCCESS_CONFIRM_BYTE) {
-- if (w1_reset_resume_command(sl->master))
-- goto error;
-- /* try again, the slave is ready for a command */
-- continue;
-+ if (w1_read_8(sl->master) == W1_F29_SUCCESS_CONFIRM_BYTE &&
-+ optional_read_back_valid(sl, *buf)) {
-+ bytes_written = 1;
-+ goto out;
- }
-
--#ifdef CONFIG_W1_SLAVE_DS2408_READBACK
-- /* here the master could read another byte which
-- would be the PIO reg (the actual pin logic state)
-- since in this driver we don't know which pins are
-- in and outs, there's no value to read the state and
-- compare. with (*buf) so end this command abruptly: */
- if (w1_reset_resume_command(sl->master))
-- goto error;
-+ goto out; /* unrecoverable error */
-+ /* try again, the slave is ready for a command */
-+ } while (--retries);
-
-- /* go read back the output latches */
-- /* (the direct effect of the write above) */
-- w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
-- w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
-- w1_buf[2] = 0;
-- w1_write_block(sl->master, w1_buf, 3);
-- /* read the result of the READ_PIO_REGS command */
-- if (w1_read_8(sl->master) == *buf)
--#endif
-- {
-- /* success! */
-- mutex_unlock(&sl->master->bus_mutex);
-- dev_dbg(&sl->dev,
-- "mutex unlocked, retries:%d", retries);
-- return 1;
-- }
-- }
--error:
-+out:
- mutex_unlock(&sl->master->bus_mutex);
-- dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
-
-- return -EIO;
-+ dev_dbg(&sl->dev, "%s, mutex unlocked retries:%d\n",
-+ (bytes_written > 0) ? "succeeded" : "error", retries);
-+
-+ return bytes_written;
- }
-
-
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