Sticky MCR bits are lost in console restoration if console suspending
has been disabled. This currently affects the AFE bit, which works in
combination with RTS which we set, so we want to make sure the UART
retains control of its FIFO where previously requested. Also specific
drivers may need other bits in the future.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Fixes: 4516d50aabed ("serial: 8250: Use canary to restart console after suspend")
Cc: stable@xxxxxxxxxxxxxxx # v4.0+
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
---
Changes from v4:
- Reorder as 1/5 (from 4/5).
New change in v4, factored out from 5/5.
---
drivers/tty/serial/8250/8250_port.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
linux-serial-8250-mcr-restore.diff
Index: linux-macro/drivers/tty/serial/8250/8250_port.c
===================================================================
--- linux-macro.orig/drivers/tty/serial/8250/8250_port.c
+++ linux-macro/drivers/tty/serial/8250/8250_port.c
@@ -3308,7 +3308,7 @@ static void serial8250_console_restore(s
serial8250_set_divisor(port, baud, quot, frac);
serial_port_out(port, UART_LCR, up->lcr);
- serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
+ serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS);
}
/*
