diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0422-w1-ds2408-reset-on-output_write-retry-with-readback.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0422-w1-ds2408-reset-on-output_write-retry-with-readback.patch | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0422-w1-ds2408-reset-on-output_write-retry-with-readback.patch b/target/linux/brcm2708/patches-4.19/950-0422-w1-ds2408-reset-on-output_write-retry-with-readback.patch new file mode 100644 index 0000000000..afdc22e2d1 --- /dev/null +++ b/target/linux/brcm2708/patches-4.19/950-0422-w1-ds2408-reset-on-output_write-retry-with-readback.patch @@ -0,0 +1,140 @@ +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; + } + + |