ARM: OMAP2+: Fix dmtimer set source clock failure

Calling the dmtimer function omap_dm_timer_set_source() fails if following a
call to pm_runtime_put() to disable the timer. For example the following
sequence would fail to set the parent clock ...

	omap_dm_timer_stop(gptimer);
	omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);

The following error message would be seen ...

omap_dm_timer_set_source: failed to set timer_32k_ck as parent

The problem is that, by design, pm_runtime_put() simply decrements the usage
count and returns before the timer has actually been disabled. Therefore,
setting the parent clock failed because the timer was still active when the
trying to set the parent clock. Setting a parent clock will fail if the clock
you are setting the parent of has a non-zero usage count. To ensure that this
does not fail use pm_runtime_put_sync() when disabling the timer.

Note that this will not be seen on OMAP1 devices, because these devices do
not use the clock framework for dmtimers.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index 626ad8cad7a9486d71408f611b4f99b46c85b995..7b6689af0cce1561b766e9b257b32fc9f0fb3dbe 100644 (file)
--- a/arch/arm/plat-omap/dmtimer.c
+++ b/arch/arm/plat-omap/dmtimer.c
@@ -258,7 +258,7 @@ EXPORT_SYMBOL_GPL(omap_dm_timer_enable);
 
 void omap_dm_timer_disable(struct omap_dm_timer *timer)
 {
-       pm_runtime_put(&timer->pdev->dev);
+       pm_runtime_put_sync(&timer->pdev->dev);
 }
 EXPORT_SYMBOL_GPL(omap_dm_timer_disable);