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+ --- 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); }
/*
On Mon, Apr 18, 2022 at 2:02 AM Maciej W. Rozycki macro@orcam.me.uk wrote:
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.
Since it's a fix it should be moved to the beginning of the series.
Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com
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+
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);}
/*
On Mon, 18 Apr 2022, Andy Shevchenko wrote:
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.
Since it's a fix it should be moved to the beginning of the series.
OK, patch reordered in v5.
Maciej
linux-stable-mirror@lists.linaro.org
-
Andy Shevchenko -
Maciej W. Rozycki