From e3af8dd4ba4fc1ae6260823dfb3a82236471c353 Mon Sep 17 00:00:00 2001 From: Phil Elwell 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 --- 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 @@ -148,6 +148,13 @@ static int bcm2835aux_serial_probe(struc */ up.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 (!up.port.uartclk) + return -EPROBE_DEFER; + /* register the port */ ret = serial8250_register_8250_port(&up); if (ret < 0) {