ARM: OMAP: Simplify dmtimer 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 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@suse.de>
[jon-hunter@ti.com: minor update to subject and changed variable name]
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>

1 files changed, 12 insertions, 20 deletions

diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
index a0daa2fb5de6..5cae1dd1f365 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;