[PATCH 6.1 122/197] serial: max310x: fail probe if clock crystal is unstable

Greg Kroah-Hartman
2024-02-20T21:04:19Z

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

commit 8afa6c6decea37e7cb473d2c60473f37f46cea35 upstream.

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>
Link: https://lore.kernel.org/r/20240116213001.3691629-4-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/max310x.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -587,7 +587,7 @@ static int max310x_update_best_err(unsig
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 de
} 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;
@@ -1285,7 +1286,7 @@ static int max310x_probe(struct device *
{
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++)
@@ -1363,6 +1364,11 @@ static int max310x_probe(struct device *
}

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++) {