diff options
| author | Rafael J. Wysocki <rjw@sisk.pl> | 2012-03-09 12:59:44 +0900 |
|---|---|---|
| committer | Paul Mundt <lethal@linux-sh.org> | 2012-03-09 12:59:44 +0900 |
| commit | 048be431e40ee32df8e6c1a2c216693afe3ee358 (patch) | |
| tree | 293a7fb0064235266683579c98acd3ad18c2bd68 | |
| parent | 948c46a195691a214811538ee4b6c0312ec15cb5 (diff) | |
sh-sci / PM: Avoid deadlocking runtime PM
The runtime PM of sh-sci devices is enabled when sci_probe() returns,
so the pm_runtime_put_sync() executed by driver_probe_device()
attempts to suspend the device. Then, in some situations, a
diagnostic message is printed to the console by one of the runtime
suspend routines handling the sh-sci device, which causes synchronous
runtime resume to be started from the device's own runtime suspend
callback. This causes rpm_resume() to be run eventually, which sees
the RPM_SUSPENDING status set by rpm_suspend() and waits for it to
change. However, the device's runtime PM status cannot change at
that point, because the routine that has set it waits for the
rpm_suspend() to return. A deadlock occurs as a result.
To avoid that make sci_init_single() increment the device's
runtime PM usage counter, so that it cannot be suspended by
driver_probe_device(). That counter has to be decremented
eventually, so make sci_startup() do that before starting to
actually use the device and make sci_shutdown() increment it
again before returning to balance the incrementation carried out by
sci_startup().
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
| -rw-r--r-- | drivers/tty/serial/sh-sci.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 75085795528e..61b7fd2729cd 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1710,6 +1710,8 @@ static int sci_startup(struct uart_port *port) dev_dbg(port->dev, "%s(%d)\n", __func__, port->line); + pm_runtime_put_noidle(port->dev); + sci_port_enable(s); ret = sci_request_irq(s); @@ -1737,6 +1739,8 @@ static void sci_shutdown(struct uart_port *port) sci_free_irq(s); sci_port_disable(s); + + pm_runtime_get_noresume(port->dev); } static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps, @@ -2075,6 +2079,7 @@ static int __devinit sci_init_single(struct platform_device *dev, sci_init_gpios(sci_port); pm_runtime_irq_safe(&dev->dev); + pm_runtime_get_noresume(&dev->dev); pm_runtime_enable(&dev->dev); } |