From: Hugo Villeneuve hvilleneuve@dimonoff.com

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 --- 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 552e153a24e0..10bf6d75bf9e 100644 --- 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 *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); @@ -1354,8 +1361,17 @@ 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); }