serial: 8250: Also set sticky MCR bits in console restoration
authorMaciej W. Rozycki <macro@orcam.me.uk>
Mon, 18 Apr 2022 15:27:10 +0000 (16:27 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 9 May 2022 07:14:30 +0000 (09:14 +0200)
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

index 723ec080679904b242d57e5f1991a5ab63797403..2285ef9477556f1ded4e73c5acb37ca07caed09a 100644 (file)
@@ -3340,7 +3340,7 @@ static void serial8250_console_restore(struct uart_8250_port *up)
 
        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);
 }
 
 /*