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authorLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>2013-11-28 18:11:45 +0100
committerSimon Horman <horms+renesas@verge.net.au>2013-12-14 09:58:12 +0900
commitcaec70381b469d6ed1bd3d0441a19aa6de0bbff3 (patch)
tree8a68b6cc78511ef077c56fecbc854dc991050dd2
parente2afca6988c335d2ec7b66f2fadcd63286570bf8 (diff)
downloadop-kernel-dev-caec70381b469d6ed1bd3d0441a19aa6de0bbff3.zip
op-kernel-dev-caec70381b469d6ed1bd3d0441a19aa6de0bbff3.tar.gz
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 <laurent.pinchart+renesas@ideasonboard.com> Acked-by: Magnus Damm <damm@opensource.se> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
-rw-r--r--drivers/tty/serial/sh-sci.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 6e5ce62..1ebac3e 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)
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