From: Will Deacon <will@kernel.org> To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, "Will Deacon" <will@kernel.org>, "Frederic Weisbecker" <fweisbec@gmail.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Marc Zyngier" <maz@kernel.org>, "Lorenzo Colitti" <lorenzo@google.com>, "John Stultz" <john.stultz@linaro.org>, "Stephen Boyd" <sboyd@kernel.org>, "Mika Penttilä" <mika.penttila@nextfour.com>, kernel-team@android.com Subject: [PATCH v2 4/5] tick/broadcast: Program wakeup timer when entering idle if required Date: Mon, 24 May 2021 23:18:17 +0100 [thread overview] Message-ID: <20210524221818.15850-5-will@kernel.org> (raw) In-Reply-To: <20210524221818.15850-1-will@kernel.org> When configuring the broadcast timer on entry to and exit from deep idle states, prefer a per-CPU wakeup timer if one exists. On entry to idle, stop the tick device and transfer the next event into the oneshot wakeup device, which will serve as the wakeup from idle. To avoid the overhead of additional hardware accesses on exit from idle, leave the timer armed and treat the inevitable interrupt as a (possibly spurious) tick event. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Marc Zyngier <maz@kernel.org> Cc: Lorenzo Colitti <lorenzo@google.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> --- kernel/time/tick-broadcast.c | 44 +++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 0e9e06d6cc5c..9b845212430b 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -96,6 +96,15 @@ static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu) return per_cpu(tick_oneshot_wakeup_device, cpu); } +static void tick_oneshot_wakeup_handler(struct clock_event_device *wd) +{ + /* + * If we woke up early and the tick was reprogrammed in the + * meantime then this may be spurious but harmless. + */ + tick_receive_broadcast(); +} + static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, int cpu) { @@ -121,6 +130,7 @@ static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, if (!try_module_get(newdev->owner)) return false; + newdev->event_handler = tick_oneshot_wakeup_handler; set_device: clockevents_exchange_device(curdev, newdev); per_cpu(tick_oneshot_wakeup_device, cpu) = newdev; @@ -909,16 +919,48 @@ static int ___tick_broadcast_oneshot_control(enum tick_broadcast_state state, return ret; } +static int tick_oneshot_wakeup_control(enum tick_broadcast_state state, + struct tick_device *td, + int cpu) +{ + struct clock_event_device *dev, *wd; + + dev = td->evtdev; + if (td->mode != TICKDEV_MODE_ONESHOT) + return -EINVAL; + + wd = tick_get_oneshot_wakeup_device(cpu); + if (!wd) + return -ENODEV; + + switch (state) { + case TICK_BROADCAST_ENTER: + clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED); + clockevents_switch_state(wd, CLOCK_EVT_STATE_ONESHOT); + clockevents_program_event(wd, dev->next_event, 1); + break; + case TICK_BROADCAST_EXIT: + /* We may have transitioned to oneshot mode while idle */ + if (clockevent_get_state(wd) != CLOCK_EVT_STATE_ONESHOT) + return -ENODEV; + } + + return 0; +} + int __tick_broadcast_oneshot_control(enum tick_broadcast_state state) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); int cpu = smp_processor_id(); + if (!tick_oneshot_wakeup_control(state, td, cpu)) + return 0; + if (tick_broadcast_device.evtdev) return ___tick_broadcast_oneshot_control(state, td, cpu); /* - * If there is no broadcast device, tell the caller not + * If there is no broadcast or wakeup device, tell the caller not * to go into deep idle. */ return -EBUSY; -- 2.31.1.818.g46aad6cb9e-goog
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org> To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, "Will Deacon" <will@kernel.org>, "Frederic Weisbecker" <fweisbec@gmail.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Marc Zyngier" <maz@kernel.org>, "Lorenzo Colitti" <lorenzo@google.com>, "John Stultz" <john.stultz@linaro.org>, "Stephen Boyd" <sboyd@kernel.org>, "Mika Penttilä" <mika.penttila@nextfour.com>, kernel-team@android.com Subject: [PATCH v2 4/5] tick/broadcast: Program wakeup timer when entering idle if required Date: Mon, 24 May 2021 23:18:17 +0100 [thread overview] Message-ID: <20210524221818.15850-5-will@kernel.org> (raw) In-Reply-To: <20210524221818.15850-1-will@kernel.org> When configuring the broadcast timer on entry to and exit from deep idle states, prefer a per-CPU wakeup timer if one exists. On entry to idle, stop the tick device and transfer the next event into the oneshot wakeup device, which will serve as the wakeup from idle. To avoid the overhead of additional hardware accesses on exit from idle, leave the timer armed and treat the inevitable interrupt as a (possibly spurious) tick event. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Marc Zyngier <maz@kernel.org> Cc: Lorenzo Colitti <lorenzo@google.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> --- kernel/time/tick-broadcast.c | 44 +++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 0e9e06d6cc5c..9b845212430b 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -96,6 +96,15 @@ static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu) return per_cpu(tick_oneshot_wakeup_device, cpu); } +static void tick_oneshot_wakeup_handler(struct clock_event_device *wd) +{ + /* + * If we woke up early and the tick was reprogrammed in the + * meantime then this may be spurious but harmless. + */ + tick_receive_broadcast(); +} + static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, int cpu) { @@ -121,6 +130,7 @@ static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, if (!try_module_get(newdev->owner)) return false; + newdev->event_handler = tick_oneshot_wakeup_handler; set_device: clockevents_exchange_device(curdev, newdev); per_cpu(tick_oneshot_wakeup_device, cpu) = newdev; @@ -909,16 +919,48 @@ static int ___tick_broadcast_oneshot_control(enum tick_broadcast_state state, return ret; } +static int tick_oneshot_wakeup_control(enum tick_broadcast_state state, + struct tick_device *td, + int cpu) +{ + struct clock_event_device *dev, *wd; + + dev = td->evtdev; + if (td->mode != TICKDEV_MODE_ONESHOT) + return -EINVAL; + + wd = tick_get_oneshot_wakeup_device(cpu); + if (!wd) + return -ENODEV; + + switch (state) { + case TICK_BROADCAST_ENTER: + clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED); + clockevents_switch_state(wd, CLOCK_EVT_STATE_ONESHOT); + clockevents_program_event(wd, dev->next_event, 1); + break; + case TICK_BROADCAST_EXIT: + /* We may have transitioned to oneshot mode while idle */ + if (clockevent_get_state(wd) != CLOCK_EVT_STATE_ONESHOT) + return -ENODEV; + } + + return 0; +} + int __tick_broadcast_oneshot_control(enum tick_broadcast_state state) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); int cpu = smp_processor_id(); + if (!tick_oneshot_wakeup_control(state, td, cpu)) + return 0; + if (tick_broadcast_device.evtdev) return ___tick_broadcast_oneshot_control(state, td, cpu); /* - * If there is no broadcast device, tell the caller not + * If there is no broadcast or wakeup device, tell the caller not * to go into deep idle. */ return -EBUSY; -- 2.31.1.818.g46aad6cb9e-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-24 22:18 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-24 22:18 [PATCH v2 0/5] tick/broadcast: Allow per-cpu timers to be used instead of broadcast Will Deacon 2021-05-24 22:18 ` Will Deacon 2021-05-24 22:18 ` [PATCH v2 1/5] tick/broadcast: Drop unneeded CONFIG_GENERIC_CLOCKEVENTS_BROADCAST guard Will Deacon 2021-05-24 22:18 ` Will Deacon 2021-05-31 15:07 ` [tip: timers/core] " tip-bot2 for Will Deacon 2021-05-24 22:18 ` [PATCH v2 2/5] tick/broadcast: Split __tick_broadcast_oneshot_control() into a helper Will Deacon 2021-05-24 22:18 ` Will Deacon 2021-05-27 7:23 ` Xin Hao 2021-05-27 7:23 ` Xin Hao 2021-05-27 8:22 ` Will Deacon 2021-05-27 8:22 ` Will Deacon 2021-05-27 11:35 ` Xin Hao 2021-05-27 11:35 ` Xin Hao 2021-05-27 11:55 ` Will Deacon 2021-05-27 11:55 ` Will Deacon 2021-05-27 11:56 ` Will Deacon 2021-05-27 11:56 ` Will Deacon 2021-05-31 14:29 ` Thomas Gleixner 2021-05-31 14:29 ` Thomas Gleixner 2021-06-01 12:13 ` Will Deacon 2021-06-01 12:13 ` Will Deacon 2021-06-01 18:14 ` Thomas Gleixner 2021-06-01 18:14 ` Thomas Gleixner 2021-05-31 15:06 ` [tip: timers/core] " tip-bot2 for Will Deacon 2021-05-24 22:18 ` [PATCH v2 3/5] tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast Will Deacon 2021-05-24 22:18 ` Will Deacon 2021-05-31 15:06 ` [tip: timers/core] " tip-bot2 for Will Deacon 2021-05-24 22:18 ` Will Deacon [this message] 2021-05-24 22:18 ` [PATCH v2 4/5] tick/broadcast: Program wakeup timer when entering idle if required Will Deacon 2021-05-31 15:06 ` [tip: timers/core] " tip-bot2 for Will Deacon 2021-05-24 22:18 ` [PATCH v2 5/5] timer_list: Print name of per-cpu wakeup device Will Deacon 2021-05-24 22:18 ` Will Deacon 2021-05-31 15:06 ` [tip: timers/core] " tip-bot2 for Will Deacon
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