From: Hugo Villeneuve hvilleneuve@dimonoff.com

A stable clock is really required in order to use this UART, so log an error message and bail out if the chip reports that the clock is not stable.

Fixes: 4cf9a888fd3c ("serial: max310x: Check the clock readiness") Cc: stable@vger.kernel.org Suggested-by: Jan Kundrát jan.kundrat@cesnet.cz Link: https://www.spinics.net/lists/linux-serial/msg35773.html Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com --- drivers/tty/serial/max310x.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index c0eb0615d945..552e153a24e0 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -587,7 +587,7 @@ static int max310x_update_best_err(unsigned long f, long *besterr) return 1; }

-static u32 max310x_set_ref_clk(struct device *dev, struct max310x_port *s, +static s32 max310x_set_ref_clk(struct device *dev, struct max310x_port *s, unsigned long freq, bool xtal) { unsigned int div, clksrc, pllcfg = 0; @@ -657,7 +657,8 @@ static u32 max310x_set_ref_clk(struct device *dev, struct max310x_port *s, } while (!stable && (++try < MAX310X_XTAL_WAIT_RETRIES));

if (!stable) - dev_warn(dev, "clock is not stable yet\n"); + return dev_err_probe(dev, -EAGAIN, + "clock is not stable\n"); }

return bestfreq; @@ -1282,7 +1283,7 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty { int i, ret, fmin, fmax, freq; struct max310x_port *s; - u32 uartclk = 0; + s32 uartclk = 0; bool xtal;

for (i = 0; i < devtype->nr; i++) @@ -1360,6 +1361,11 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty }

uartclk = max310x_set_ref_clk(dev, s, freq, xtal); + if (uartclk < 0) { + ret = uartclk; + goto out_uart; + } + dev_dbg(dev, "Reference clock set to %i Hz\n", uartclk);

for (i = 0; i < devtype->nr; i++) {