Hi, Grygorii Strashko <grygorii.stras...@ti.com> writes: > Now the System stall is observed on TI AM437x based board > (am437x-gp-evm) during resuming from System suspend when ARM Global > timer is selected as clocksource device - SysRq are working, but > nothing else. The reason of stall is that ARM Global timer loses its > contexts. > > The reason of stall is that ARM Global timer loses its contexts during > System suspend: > GT_CONTROL.TIMER_ENABLE = 0 (unbanked) > GT_COUNTERx = 0 > > Hence, update ARM Global timer driver to reflect above behaviour > - save GT_CONTROL.TIMER_ENABLE during suspend and restore on resume; > - ensure clocksource and clockevent devices have coresponding flags > (CLOCK_SOURCE_SUSPEND_NONSTOP and CLOCK_EVT_FEAT_C3STOP) set > depending on presence of "always-on" DT property. > > CC: Arnd Bergmann <a...@arndb.de> > Cc: John Stultz <john.stu...@linaro.org> > Cc: Felipe Balbi <ba...@ti.com> > Cc: Tony Lindgren <t...@atomide.com> > Signed-off-by: Grygorii Strashko <grygorii.stras...@ti.com> > --- > drivers/clocksource/arm_global_timer.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/clocksource/arm_global_timer.c > b/drivers/clocksource/arm_global_timer.c > index a2cb6fa..1bbaf64 100644 > --- a/drivers/clocksource/arm_global_timer.c > +++ b/drivers/clocksource/arm_global_timer.c > @@ -51,6 +51,8 @@ static void __iomem *gt_base; > static unsigned long gt_clk_rate; > static int gt_ppi; > static struct clock_event_device __percpu *gt_evt; > +static bool gt_always_on; > +static u32 gt_control; > > /* > * To get the value from the Global Timer Counter register proceed as > follows: > @@ -168,6 +170,9 @@ static int gt_clockevents_init(struct clock_event_device > *clk) > { > int cpu = smp_processor_id(); > > + if (!gt_always_on) > + clk->features |= CLOCK_EVT_FEAT_C3STOP; > + > clk->name = "arm_global_timer"; > clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | > CLOCK_EVT_FEAT_PERCPU; > @@ -195,12 +200,25 @@ static cycle_t gt_clocksource_read(struct clocksource > *cs) > return gt_counter_read(); > } > > +static void gt_suspend(struct clocksource *cs) > +{ > + gt_control = readl(gt_base + GT_CONTROL); > +} > + > +static void gt_resume(struct clocksource *cs) > +{ > + /* enables timer on all the cores */ > + writel(gt_control & GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
do you really need to save context if all you restore is TIMER_ENABLE bit ? seems like you could skip gt_suspend altogether. Is there really a situation where this driver is running and GT isn't enabled ? -- balbi
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