diff mbox series

[5.4,24/84] serial: 8250: Also set sticky MCR bits in console restoration

Message ID 20220504152929.482826578@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH May 4, 2022, 4:44 p.m. UTC 
From: Maciej W. Rozycki <macro@orcam.me.uk>

commit 6e6eebdf5e2455f089ccd000754a0deaeb79af82 upstream.

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@orcam.me.uk>
Fixes: 4516d50aabed ("serial: 8250: Use canary to restart console after suspend")
Cc: stable@vger.kernel.org # v4.0+
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181518490.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/8250/8250_port.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3184,7 +3184,7 @@  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);
 }
 
 /*