This is a note to let you know that I've just added the patch titled
serial: max310x: prevent infinite while() loop in port startup
to the 6.6-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-prevent-infinite-while-loop-in-port-startup.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b35f8dbbce818b02c730dc85133dc7754266e084 Mon Sep 17 00:00:00 2001
From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Date: Tue, 16 Jan 2024 16:30:01 -0500
Subject: serial: max310x: prevent infinite while() loop in port startup
From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
commit b35f8dbbce818b02c730dc85133dc7754266e084 upstream.
If there is a problem after resetting a port, the do/while() loop that
checks the default value of DIVLSB register may run forever and spam the
I2C bus.
Add a delay before each read of DIVLSB, and a maximum number of tries to
prevent that situation from happening.
Also fail probe if port reset is unsuccessful.
Fixes: 10d8b34a4217 ("serial: max310x: Driver rework")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240116213001.3691629-5-hugo@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/max310x.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -237,6 +237,10 @@
#define MAX310x_REV_MASK (0xf8)
#define MAX310X_WRITE_BIT 0x80
+/* Port startup definitions */
+#define MAX310X_PORT_STARTUP_WAIT_RETRIES 20 /* Number of retries */
+#define MAX310X_PORT_STARTUP_WAIT_DELAY_MS 10 /* Delay between retries */
+
/* Crystal-related definitions */
#define MAX310X_XTAL_WAIT_RETRIES 20 /* Number of retries */
#define MAX310X_XTAL_WAIT_DELAY_MS 10 /* Delay between retries */
@@ -1346,6 +1350,9 @@ static int max310x_probe(struct device *
goto out_clk;
for (i = 0; i < devtype->nr; i++) {
+ bool started = false;
+ unsigned int try = 0, val = 0;
+
/* Reset port */
regmap_write(regmaps[i], MAX310X_MODE2_REG,
MAX310X_MODE2_RST_BIT);
@@ -1354,8 +1361,17 @@ static int max310x_probe(struct device *
/* Wait for port startup */
do {
- regmap_read(regmaps[i], MAX310X_BRGDIVLSB_REG, &ret);
- } while (ret != 0x01);
+ msleep(MAX310X_PORT_STARTUP_WAIT_DELAY_MS);
+ regmap_read(regmaps[i], MAX310X_BRGDIVLSB_REG, &val);
+
+ if (val == 0x01)
+ started = true;
+ } while (!started && (++try < MAX310X_PORT_STARTUP_WAIT_RETRIES));
+
+ if (!started) {
+ ret = dev_err_probe(dev, -EAGAIN, "port reset failed\n");
+ goto out_uart;
+ }
regmap_write(regmaps[i], MAX310X_MODE1_REG, devtype->mode1);
}
Patches currently in stable-queue which might be from hvilleneuve@xxxxxxxxxxxx are
queue-6.6/serial-max310x-fail-probe-if-clock-crystal-is-unstable.patch
queue-6.6/serial-max310x-prevent-infinite-while-loop-in-port-startup.patch
queue-6.6/serial-max310x-set-default-value-when-reading-clock-ready-bit.patch
queue-6.6/serial-max310x-improve-crystal-stable-clock-detection.patch
