openwrt/target/linux/bcm27xx/patches-5.4/950-0843-serial-8250-bcm2835aux-defer-if-clock-is-zero.patch
Álvaro Fernández Rojas f07e572f64 bcm27xx: import latest patches from the RPi foundation
bcm2708: boot tested on RPi B+ v1.2
bcm2709: boot tested on RPi 3B v1.2 and RPi 4B v1.1 4G
bcm2710: boot tested on RPi 3B v1.2
bcm2711: boot tested on RPi 4B v1.1 4G

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2021-02-18 23:42:32 +01:00

29 lines
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Diff

From 80163961af8e31a2045271c5a12adaae620445e1 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Thu, 2 Jul 2020 13:53:20 +0100
Subject: [PATCH] serial: 8250: bcm2835aux - defer if clock is zero
See: https://github.com/raspberrypi/linux/issues/3700
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/tty/serial/8250/8250_bcm2835aux.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/tty/serial/8250/8250_bcm2835aux.c
+++ b/drivers/tty/serial/8250/8250_bcm2835aux.c
@@ -92,6 +92,13 @@ static int bcm2835aux_serial_probe(struc
*/
data->uart.port.uartclk = clk_get_rate(data->clk) * 2;
+ /* The clock is only queried at probe time, which means we get one shot
+ * at this. A zero clock is never going to work and is almost certainly
+ * due to a parent not being ready, so prefer to defer.
+ */
+ if (!data->uart.port.uartclk)
+ return -EPROBE_DEFER;
+
/* register the port */
ret = serial8250_register_8250_port(&data->uart);
if (ret < 0) {