OMAP dmtimer - simplify context-loss handling.

The context loss handling in dmtimer appears to assume that
   omap_dm_timer_set_load_start() or omap_dm_timer_start()
and
   omap_dm_timer_stop()

bracket all interactions.  Only the first two restore the context and
the last updates the context loss counter.
However omap_dm_timer_set_load() or omap_dm_timer_set_match() can
reasonably be call outside this bracketing, and the fact that they
call omap_dm_timer_enable() / omap_dm_timer_disable() suggest that
is expected.

So if, after a transition into and out of off-mode, which would cause
the dm timer to loose all state, omap_dm_timer_set_match() is called
before omap_dm_timer_start(), the value read from OMAP_TIMER_CTRL_REG
will be 'wrong' and this wrong value will be stored context.tclr so
a subsequent omap_dm_timer_start() can fail (As the control register
is wrong).

Simplify this be doing the restore-from-context in
omap_dm_timer_enable() so that whenever the timer is enabled, the
context is correct.
Also update the ctx_loss_count at the same time as we notice it is
wrong - these is no value in delaying this until the
omap_dm_timer_disable() as it cannot change while the timer is
enabled.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 9 insertions, 20 deletions

diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index 7b433f3..628196d 100644
--- a/arch/arm/plat-omap/dmtimer.c
+++ b/arch/arm/plat-omap/dmtimer.c
@@ -316,6 +316,15 @@ EXPORT_SYMBOL_GPL(omap_dm_timer_free);
 void omap_dm_timer_enable(struct omap_dm_timer *timer)
 {
 	pm_runtime_get_sync(&timer->pdev->dev);
+
+	if (!(timer->capability & OMAP_TIMER_ALWON)) {
+		int loss_count =
+			timer->get_context_loss_count(&timer->pdev->dev);
+		if (loss_count != timer->ctx_loss_count) {
+			omap_timer_restore_context(timer);
+			timer->ctx_loss_count = loss_count;
+		}
+	}
 }
 EXPORT_SYMBOL_GPL(omap_dm_timer_enable);
 
@@ -410,13 +419,6 @@ int omap_dm_timer_start(struct omap_dm_timer *timer)
 
 	omap_dm_timer_enable(timer);
 
-	if (!(timer->capability & OMAP_TIMER_ALWON)) {
-		if (timer->get_context_loss_count &&
-			timer->get_context_loss_count(&timer->pdev->dev) !=
-				timer->ctx_loss_count)
-			omap_timer_restore_context(timer);
-	}
-
 	l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG);
 	if (!(l & OMAP_TIMER_CTRL_ST)) {
 		l |= OMAP_TIMER_CTRL_ST;
@@ -441,12 +443,6 @@ int omap_dm_timer_stop(struct omap_dm_timer *timer)
 
 	__omap_dm_timer_stop(timer, timer->posted, rate);
 
-	if (!(timer->capability & OMAP_TIMER_ALWON)) {
-		if (timer->get_context_loss_count)
-			timer->ctx_loss_count =
-				timer->get_context_loss_count(&timer->pdev->dev);
-	}
-
 	/*
 	 * Since the register values are computed and written within
 	 * __omap_dm_timer_stop, we need to use read to retrieve the
@@ -553,13 +549,6 @@ int omap_dm_timer_set_load_start(struct omap_dm_timer *timer, int autoreload,
 
 	omap_dm_timer_enable(timer);
 
-	if (!(timer->capability & OMAP_TIMER_ALWON)) {
-		if (timer->get_context_loss_count &&
-			timer->get_context_loss_count(&timer->pdev->dev) !=
-				timer->ctx_loss_count)
-			omap_timer_restore_context(timer);
-	}
-
 	l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG);
 	if (autoreload) {
 		l |= OMAP_TIMER_CTRL_AR;