clocksource/drivers/exynos_mct: Increase priority over ARM arch timer

[ Upstream commit 6282edb72bed5324352522d732080d4c1b9dfed6 ]

Exynos SoCs based on CA7/CA15 have 2 timer interfaces: custom Exynos MCT
(Multi Core Timer) and standard ARM Architected Timers.

There are use cases, where both timer interfaces are used simultanously.
One of such examples is using Exynos MCT for the main system timer and
ARM Architected Timers for the KVM and virtualized guests (KVM requires
arch timers).

Exynos Multi-Core Timer driver (exynos_mct) must be however started
before ARM Architected Timers (arch_timer), because they both share some
common hardware blocks (global system counter) and turning on MCT is
needed to get ARM Architected Timer working properly.

To ensure selecting Exynos MCT as the main system timer, increase MCT
timer rating. To ensure proper starting order of both timers during
suspend/resume cycle, increase MCT hotplug priority over ARM Archictected
Timers.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 34bd250d46c6ce26f796611f5dca6b4dceb52387..6aa10cbc1d59d430b4b68df0c7621c95685ea755 100644 (file)
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -209,7 +209,7 @@ static void exynos4_frc_resume(struct clocksource *cs)
 
 static struct clocksource mct_frc = {
        .name           = "mct-frc",
-       .rating         = 400,
+       .rating         = 450,  /* use value higher than ARM arch timer */
        .read           = exynos4_frc_read,
        .mask           = CLOCKSOURCE_MASK(32),
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
@@ -464,7 +464,7 @@ 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 = 450;
+       evt->rating = 500;      /* use value higher than ARM arch timer */
 
        exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET);
 

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index dec95654f3ae0042f238ffb55af521a13a8d6de4..04c4a478323bd0fed8352cea950d4b551fe1eedc 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -116,10 +116,10 @@ enum cpuhp_state {
        CPUHP_AP_PERF_ARM_ACPI_STARTING,
        CPUHP_AP_PERF_ARM_STARTING,
        CPUHP_AP_ARM_L2X0_STARTING,
+       CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
        CPUHP_AP_ARM_ARCH_TIMER_STARTING,
        CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
        CPUHP_AP_JCORE_TIMER_STARTING,
-       CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
        CPUHP_AP_ARM_TWD_STARTING,
        CPUHP_AP_QCOM_TIMER_STARTING,
        CPUHP_AP_TEGRA_TIMER_STARTING,