From: Hugo Villeneuve hvilleneuve@dimonoff.com
[ Upstream commit b35f8dbbce818b02c730dc85133dc7754266e084 ]
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@vger.kernel.org Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com Link: https://lore.kernel.org/r/20240116213001.3691629-5-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/max310x.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index 80298a5714bcb..978d9d93127e5 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -235,6 +235,10 @@ #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 */ @@ -1316,6 +1320,9 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty 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); @@ -1324,8 +1331,17 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty
/* 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); }