Patch "serial: max310x: fail probe if clock crystal is unstable" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    serial: max310x: fail probe if clock crystal is unstable

to the 5.10-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-fail-probe-if-clock-crystal-is-unstab.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0545f60f222499c7ab4f10ef0b2cd8a6c17cf290
Author: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Date:   Tue Jan 16 16:30:00 2024 -0500

    serial: max310x: fail probe if clock crystal is unstable
    
    [ Upstream commit 8afa6c6decea37e7cb473d2c60473f37f46cea35 ]
    
    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@xxxxxxxxxxxxxxx
    Suggested-by: Jan Kundrát <jan.kundrat@xxxxxxxxx>
    Link: https://www.spinics.net/lists/linux-serial/msg35773.html
    Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240116213001.3691629-4-hugo@xxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 0e0f778d75cd4..bbf45c0626681 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -556,7 +556,7 @@ 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;
@@ -626,7 +626,8 @@ 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;
@@ -1266,7 +1267,7 @@ static int max310x_probe(struct device *dev, struct max310x_devtype *devtype,
 {
 	int i, ret, fmin, fmax, freq;
 	struct max310x_port *s;
-	u32 uartclk = 0;
+	s32 uartclk = 0;
 	bool xtal;
 
 	if (IS_ERR(regmap))
@@ -1350,6 +1351,11 @@ static int max310x_probe(struct device *dev, struct max310x_devtype *devtype,
 	}
 
 	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++) {