ARM: OMAP: Simplify dmtimer context-loss handling (9cc268d5) · Commits · 戴 / test

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>

arch/arm/plat-omap/dmtimer.c

+12 −20

Original line number	Diff line number	Diff line
		@@ -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;

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