From caec70381b469d6ed1bd3d0441a19aa6de0bbff3 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 28 Nov 2013 18:11:45 +0100 Subject: serial: sh-sci: Don't enable/disable port from within break timer The break timer accesses hardware registers and thus requires the port to be enabled. It currently ensures this by enabling the port at the beginning of the timer handler, and disabling it at the end. However, the enable/disable operations call the runtime PM sync functions, which are not allowed in atomic context. The current situation is thus broken. This change relies on non-atomic code to enable/disable the port. The break timer will only be started from the IRQ handler, which already runs with the port enabled. We just need to ensure that the port won't be disabled with the timer running, and that's easily done by just cancelling the timer in the port disable function. Signed-off-by: Laurent Pinchart Acked-by: Magnus Damm Acked-by: Greg Kroah-Hartman Signed-off-by: Simon Horman --- drivers/tty/serial/sh-sci.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 6e5ce628b4eb..1ebac3e9e53a 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -431,6 +431,14 @@ static void sci_port_disable(struct sci_port *sci_port) if (!sci_port->port.dev) return; + /* Cancel the break timer to ensure that the timer handler will not try + * to access the hardware with clocks and power disabled. Reset the + * break flag to make the break debouncing state machine ready for the + * next break. + */ + del_timer_sync(&sci_port->break_timer); + sci_port->break_flag = 0; + clk_disable(sci_port->fclk); clk_disable(sci_port->iclk); @@ -733,8 +741,6 @@ static void sci_break_timer(unsigned long data) { struct sci_port *port = (struct sci_port *)data; - sci_port_enable(port); - if (sci_rxd_in(&port->port) == 0) { port->break_flag = 1; sci_schedule_break_timer(port); @@ -744,8 +750,6 @@ static void sci_break_timer(unsigned long data) sci_schedule_break_timer(port); } else port->break_flag = 0; - - sci_port_disable(port); } static int sci_handle_errors(struct uart_port *port) -- cgit v1.2.1