This is a note to let you know that I've just added the patch titled
serial: max310x: fix IO data corruption in batched operations
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-max310x-fix-io-data-corruption-in-batched-operations.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3f42b142ea1171967e40e10e4b0241c0d6d28d41 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Kundr=C3=A1t?= <jan.kundrat@xxxxxxxxx>
Date: Wed, 5 Apr 2023 22:14:23 +0200
Subject: serial: max310x: fix IO data corruption in batched operations
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Jan Kundrát <jan.kundrat@xxxxxxxxx>
commit 3f42b142ea1171967e40e10e4b0241c0d6d28d41 upstream.
After upgrading from 5.16 to 6.1, our board with a MAX14830 started
producing lots of garbage data over UART. Bisection pointed out commit
285e76fc049c as the culprit. That patch tried to replace hand-written
code which I added in 2b4bac48c1084 ("serial: max310x: Use batched reads
when reasonably safe") with the generic regmap infrastructure for
batched operations.
Unfortunately, the `regmap_raw_read` and `regmap_raw_write` which were
used are actually functions which perform IO over *multiple* registers.
That's not what is needed for accessing these Tx/Rx FIFOs; the
appropriate functions are the `_noinc_` versions, not the `_raw_` ones.
Fix this regression by using `regmap_noinc_read()` and
`regmap_noinc_write()` along with the necessary `regmap_config` setup;
with this patch in place, our board communicates happily again. Since
our board uses SPI for talking to this chip, the I2C part is completely
untested.
Fixes: 285e76fc049c ("serial: max310x: use regmap methods for SPI batch operations")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Jan Kundrát <jan.kundrat@xxxxxxxxx>
Link: https://lore.kernel.org/r/79db8e82aadb0e174bc82b9996423c3503c8fb37.1680732084.git.jan.kundrat@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/max310x.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -525,6 +525,11 @@ static bool max310x_reg_precious(struct
return false;
}
+static bool max310x_reg_noinc(struct device *dev, unsigned int reg)
+{
+ return reg == MAX310X_RHR_REG;
+}
+
static int max310x_set_baud(struct uart_port *port, int baud)
{
unsigned int mode = 0, div = 0, frac = 0, c = 0, F = 0;
@@ -651,14 +656,14 @@ static void max310x_batch_write(struct u
{
struct max310x_one *one = to_max310x_port(port);
- regmap_raw_write(one->regmap, MAX310X_THR_REG, txbuf, len);
+ regmap_noinc_write(one->regmap, MAX310X_THR_REG, txbuf, len);
}
static void max310x_batch_read(struct uart_port *port, u8 *rxbuf, unsigned int len)
{
struct max310x_one *one = to_max310x_port(port);
- regmap_raw_read(one->regmap, MAX310X_RHR_REG, rxbuf, len);
+ regmap_noinc_read(one->regmap, MAX310X_RHR_REG, rxbuf, len);
}
static void max310x_handle_rx(struct uart_port *port, unsigned int rxlen)
@@ -1468,6 +1473,10 @@ static struct regmap_config regcfg = {
.writeable_reg = max310x_reg_writeable,
.volatile_reg = max310x_reg_volatile,
.precious_reg = max310x_reg_precious,
+ .writeable_noinc_reg = max310x_reg_noinc,
+ .readable_noinc_reg = max310x_reg_noinc,
+ .max_raw_read = MAX310X_FIFO_SIZE,
+ .max_raw_write = MAX310X_FIFO_SIZE,
};
#ifdef CONFIG_SPI_MASTER
@@ -1553,6 +1562,10 @@ static struct regmap_config regcfg_i2c =
.volatile_reg = max310x_reg_volatile,
.precious_reg = max310x_reg_precious,
.max_register = MAX310X_I2C_REVID_EXTREG,
+ .writeable_noinc_reg = max310x_reg_noinc,
+ .readable_noinc_reg = max310x_reg_noinc,
+ .max_raw_read = MAX310X_FIFO_SIZE,
+ .max_raw_write = MAX310X_FIFO_SIZE,
};
static const struct max310x_if_cfg max310x_i2c_if_cfg = {
Patches currently in stable-queue which might be from jan.kundrat@xxxxxxxxx are
queue-6.3/serial-max310x-fix-io-data-corruption-in-batched-operations.patch
