From e6da7808c955e609b3adf9d18b02f94463616016 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Wed, 21 Sep 2022 00:35:32 +0100 Subject: serial: 8250: Let drivers request full 16550A feature probing [ Upstream commit 9906890c89e4dbd900ed87ad3040080339a7f411 ] A SERIAL_8250_16550A_VARIANTS configuration option has been recently defined that lets one request the 8250 driver not to probe for 16550A device features so as to reduce the driver's device startup time in virtual machines. Some actual hardware devices require these features to have been fully determined however for their driver to work correctly, so define a flag to let drivers request full 16550A feature probing on a device-by-device basis if required regardless of the SERIAL_8250_16550A_VARIANTS option setting chosen. Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes of 16550A variants") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Anders Blomdell Signed-off-by: Maciej W. Rozycki Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209202357520.41633@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_port.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 8b3756e4bb05..f648fd1d7548 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1023,7 +1023,8 @@ static void autoconfig_16550a(struct uart_8250_port *up) up->port.type = PORT_16550A; up->capabilities |= UART_CAP_FIFO; - if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS)) + if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS) && + !(up->port.flags & UPF_FULL_PROBE)) return; /* -- cgit v1.2.3