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 --- 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); }
/*