From: NeilBrown <neilb@xxxxxxx>
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 called 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@xxxxxxx>
[jon-hunter@xxxxxx: minor update to subject and changed variable name]
Signed-off-by: Jon Hunter <jon-hunter@xxxxxx>
---
arch/arm/plat-omap/dmtimer.c | 32 ++++++++++++--------------------
1 file changed, 12 insertions(+), 20 deletions(-)
diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index a0daa2f..5cae1dd 100644
--- a/arch/arm/plat-omap/dmtimer.c
+++ b/arch/arm/plat-omap/dmtimer.c
@@ -315,7 +315,19 @@ EXPORT_SYMBOL_GPL(omap_dm_timer_free);
void omap_dm_timer_enable(struct omap_dm_timer *timer)
{
+ int c;
+
pm_runtime_get_sync(&timer->pdev->dev);
+
+ if (!(timer->capability & OMAP_TIMER_ALWON)) {
+ if (timer->get_context_loss_count) {
+ c = timer->get_context_loss_count(&timer->pdev->dev);
+ if (c != timer->ctx_loss_count) {
+ omap_timer_restore_context(timer);
+ timer->ctx_loss_count = c;
+ }
+ }
+ }
}
EXPORT_SYMBOL_GPL(omap_dm_timer_enable);
@@ -410,13 +422,6 @@ 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 +446,6 @@ 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 +552,6 @@ 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;
--
1.7.10.4
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