Messages in this thread | | | Date | Thu, 17 Jun 2021 22:47:48 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 1/2] clocksource/drivers/exynos_mct: Prioritise Arm arch timer on arm64 |
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On Thu, Jun 17, 2021 at 09:58:35AM +0900, Chanwoo Choi wrote: > On 6/17/21 12:25 AM, Daniel Lezcano wrote: > > On 10/06/2021 03:03, Chanwoo Choi wrote: > >> On 6/9/21 12:43 AM, Will Deacon wrote: > >>> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c > >>> index fabad79baafc..804d3e01c8f4 100644 > >>> --- a/drivers/clocksource/exynos_mct.c > >>> +++ b/drivers/clocksource/exynos_mct.c > >>> @@ -51,6 +51,15 @@ > >>> > >>> #define TICK_BASE_CNT 1 > >>> > >>> +#ifdef CONFIG_ARM > >>> +/* Use values higher than ARM arch timer. See 6282edb72bed. */ > >>> +#define MCT_CLKSOURCE_RATING 450 > >>> +#define MCT_CLKEVENTS_RATING 500 > >>> +#else > >>> +#define MCT_CLKSOURCE_RATING 350 > >>> +#define MCT_CLKEVENTS_RATING 350 > >>> +#endif > >>> + > >>> enum { > >>> MCT_INT_SPI, > >>> MCT_INT_PPI > >>> @@ -206,7 +215,7 @@ static void exynos4_frc_resume(struct clocksource *cs) > >>> > >>> static struct clocksource mct_frc = { > >>> .name = "mct-frc", > >>> - .rating = 450, /* use value higher than ARM arch timer */ > >>> + .rating = MCT_CLKSOURCE_RATING, > >>> .read = exynos4_frc_read, > >>> .mask = CLOCKSOURCE_MASK(32), > >>> .flags = CLOCK_SOURCE_IS_CONTINUOUS, > >>> @@ -457,7 +466,7 @@ static int exynos4_mct_starting_cpu(unsigned int cpu) > >>> evt->set_state_oneshot_stopped = set_state_shutdown; > >>> evt->tick_resume = set_state_shutdown; > >>> evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; > >>> - evt->rating = 500; /* use value higher than ARM arch timer */ > >>> + evt->rating = MCT_CLKEVENTS_RATING, > >>> > >>> exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET); > >>> > >>> > >> > >> I'm not sure that exynos mct is working without problem > >> such as the case of 6282edb72bed. > >> As described on On ,6282edb72bed the arch timer on exynos SoC > >> depends on Exynos MCT device. the arch timer is not able to work > >> without Exynos MCT because of using the common module. > > > > Is it possible to change the DT to have a phandle to the exynos_mct, so > > it will be probed before the arch_arm_timer ? > > I think that DT changes is not proper way to keep the order between > exynos_mct and arch timer.
exynos4_mct_frc_start() is called unconditionally from probe via exynos4_clocksource_init() so as long as the mct probes first, then the arch timer should work, no? The rating shouldn't affect that.
Will
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