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Date: Wed, 25 Mar 2015 08:34:12 -0400 (EDT)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, mingo@...nel.org, tglx@...utronix.de,
Linux PM list <linux-pm@...r.kernel.org>,
Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH 09/09] arm: bl_switcher: Kill tick suspend hackery
On Wed, 25 Mar 2015, Rafael J. Wysocki wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
>
> Use the new tick_suspend/resume_local() and get rid of the homebrewn
> implementation of these in the ARM bL switcher. The check for the
> cpumask is completely pointless. There is no harm to suspend a per
> cpu tick device unconditionally. If that's a real issue then we fix
> it proper at the core level and not with some completely undocumented
> hacks in some random core code.
>
> Move the tick internals to the core code, now that this nuisance is
> gone.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Nicolas Pitre <nicolas.pitre@...aro.org>
> Cc: Russell King <rmk+kernel@....linux.org.uk>
> [ rjw: Rebase, changelog ]
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Nicolas Pitre <nicolas.pitre@...aro.org>
> ---
> arch/arm/common/bL_switcher.c | 16 ++--------------
> include/linux/clockchips.h | 6 ------
> include/linux/tick.h | 19 ++++---------------
> kernel/time/tick-common.c | 2 +-
> kernel/time/tick-internal.h | 5 +++++
> kernel/time/tick-sched.h | 10 ++++++++++
> 6 files changed, 22 insertions(+), 36 deletions(-)
>
> Index: linux-pm/include/linux/tick.h
> ===================================================================
> --- linux-pm.orig/include/linux/tick.h
> +++ linux-pm/include/linux/tick.h
> @@ -11,30 +11,19 @@
> #include <linux/cpumask.h>
> #include <linux/sched.h>
>
> -/* ARM BL switcher abuse support */
> -#ifdef CONFIG_GENERIC_CLOCKEVENTS
> -enum tick_device_mode {
> - TICKDEV_MODE_PERIODIC,
> - TICKDEV_MODE_ONESHOT,
> -};
> -
> -struct tick_device {
> - struct clock_event_device *evtdev;
> - enum tick_device_mode mode;
> -};
> -extern struct tick_device *tick_get_device(int cpu);
> -#endif
> -
> #ifdef CONFIG_GENERIC_CLOCKEVENTS
> extern void __init tick_init(void);
> extern void tick_freeze(void);
> extern void tick_unfreeze(void);
> -/* Should be core only, but XEN resume magic requires this */
> +/* Should be core only, but ARM BL switcher requires it */
> +extern void tick_suspend_local(void);
> +/* Should be core only, but XEN resume magic and ARM BL switcher require it */
> extern void tick_resume_local(void);
> #else /* CONFIG_GENERIC_CLOCKEVENTS */
> static inline void tick_init(void) { }
> static inline void tick_freeze(void) { }
> static inline void tick_unfreeze(void) { }
> +static inline void tick_suspend_local(void) { }
> static inline void tick_resume_local(void) { }
> #endif /* !CONFIG_GENERIC_CLOCKEVENTS */
>
> Index: linux-pm/arch/arm/common/bL_switcher.c
> ===================================================================
> --- linux-pm.orig/arch/arm/common/bL_switcher.c
> +++ linux-pm/arch/arm/common/bL_switcher.c
> @@ -151,8 +151,6 @@ static int bL_switch_to(unsigned int new
> unsigned int mpidr, this_cpu, that_cpu;
> unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster;
> struct completion inbound_alive;
> - struct tick_device *tdev;
> - enum clock_event_mode tdev_mode;
> long volatile *handshake_ptr;
> int ipi_nr, ret;
>
> @@ -219,13 +217,7 @@ static int bL_switch_to(unsigned int new
> /* redirect GIC's SGIs to our counterpart */
> gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]);
>
> - tdev = tick_get_device(this_cpu);
> - if (tdev && !cpumask_equal(tdev->evtdev->cpumask, cpumask_of(this_cpu)))
> - tdev = NULL;
> - if (tdev) {
> - tdev_mode = tdev->evtdev->mode;
> - clockevents_set_mode(tdev->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
> - }
> + tick_suspend_local();
>
> ret = cpu_pm_enter();
>
> @@ -251,11 +243,7 @@ static int bL_switch_to(unsigned int new
>
> ret = cpu_pm_exit();
>
> - if (tdev) {
> - clockevents_set_mode(tdev->evtdev, tdev_mode);
> - clockevents_program_event(tdev->evtdev,
> - tdev->evtdev->next_event, 1);
> - }
> + tick_resume_local();
>
> trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr);
> local_fiq_enable();
> Index: linux-pm/include/linux/clockchips.h
> ===================================================================
> --- linux-pm.orig/include/linux/clockchips.h
> +++ linux-pm/include/linux/clockchips.h
> @@ -163,12 +163,6 @@ clockevents_calc_mult_shift(struct clock
> freq, minsec);
> }
>
> -/* Should be core only, but is abused by arm bl_switcher */
> -extern void clockevents_set_mode(struct clock_event_device *dev,
> - enum clock_event_mode mode);
> -extern int clockevents_program_event(struct clock_event_device *dev,
> - ktime_t expires, bool force);
> -
> extern void clockevents_suspend(void);
> extern void clockevents_resume(void);
>
> Index: linux-pm/kernel/time/tick-internal.h
> ===================================================================
> --- linux-pm.orig/kernel/time/tick-internal.h
> +++ linux-pm/kernel/time/tick-internal.h
> @@ -28,6 +28,7 @@ extern bool tick_check_replacement(struc
> struct clock_event_device *newdev);
> extern void tick_install_replacement(struct clock_event_device *dev);
> extern int tick_is_oneshot_available(void);
> +extern struct tick_device *tick_get_device(int cpu);
>
> /* Check, if the device is functional or a dummy for broadcast */
> static inline int tick_device_is_functional(struct clock_event_device *dev)
> @@ -38,6 +39,10 @@ static inline int tick_device_is_functio
> extern void clockevents_shutdown(struct clock_event_device *dev);
> extern void clockevents_exchange_device(struct clock_event_device *old,
> struct clock_event_device *new);
> +extern void clockevents_set_mode(struct clock_event_device *dev,
> + enum clock_event_mode mode);
> +extern int clockevents_program_event(struct clock_event_device *dev,
> + ktime_t expires, bool force);
> extern void clockevents_handle_noop(struct clock_event_device *dev);
> extern int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
> extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt);
> Index: linux-pm/kernel/time/tick-sched.h
> ===================================================================
> --- linux-pm.orig/kernel/time/tick-sched.h
> +++ linux-pm/kernel/time/tick-sched.h
> @@ -3,6 +3,16 @@
>
> #include <linux/hrtimer.h>
>
> +enum tick_device_mode {
> + TICKDEV_MODE_PERIODIC,
> + TICKDEV_MODE_ONESHOT,
> +};
> +
> +struct tick_device {
> + struct clock_event_device *evtdev;
> + enum tick_device_mode mode;
> +};
> +
> enum tick_nohz_mode {
> NOHZ_MODE_INACTIVE,
> NOHZ_MODE_LOWRES,
> Index: linux-pm/kernel/time/tick-common.c
> ===================================================================
> --- linux-pm.orig/kernel/time/tick-common.c
> +++ linux-pm/kernel/time/tick-common.c
> @@ -379,7 +379,7 @@ void tick_shutdown(unsigned int *cpup)
> *
> * No locks required. Nothing can change the per cpu device.
> */
> -static void tick_suspend_local(void)
> +void tick_suspend_local(void)
> {
> struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
>
>
>
--
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