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Date: Tue, 12 Feb 2013 16:00:16 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Len Brown <lenb@...nel.org>
CC: linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, Len Brown <len.brown@...el.com>,
Jiri Kosina <jkosina@...e.cz>
Subject: Re: [PATCH v2] APM idle: register apm_cpu_idle via cpuidle
On 02/12/2013 12:03 AM, Len Brown wrote:
> From: Len Brown <len.brown@...el.com>
>
> Update APM to register its local idle routine with cpuidle.
>
> This allows us to stop exporting pm_idle to modules on x86.
>
> The Kconfig sub-option, APM_CPU_IDLE, now depends on on CPU_IDLE.
>
> Compile-tested only.
>
> Signed-off-by: Len Brown <len.brown@...el.com>
> Cc: Jiri Kosina <jkosina@...e.cz>
> ---
> v2: updates from Daniel Lezcano's review
> ---
> arch/x86/Kconfig | 1 +
> arch/x86/kernel/apm_32.c | 60 +++++++++++++++++++++++++++++------------------
> arch/x86/kernel/process.c | 3 ---
> 3 files changed, 38 insertions(+), 26 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 225543b..1b63586 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1912,6 +1912,7 @@ config APM_DO_ENABLE
> this feature.
>
> config APM_CPU_IDLE
> + depends on CPU_IDLE
> bool "Make CPU Idle calls when idle"
> ---help---
> Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
> diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
> index d65464e..f9f8afc 100644
> --- a/arch/x86/kernel/apm_32.c
> +++ b/arch/x86/kernel/apm_32.c
> @@ -232,6 +232,7 @@
> #include <linux/acpi.h>
> #include <linux/syscore_ops.h>
> #include <linux/i8253.h>
> +#include <linux/cpuidle.h>
>
> #include <asm/uaccess.h>
> #include <asm/desc.h>
> @@ -360,13 +361,38 @@ struct apm_user {
> * idle percentage above which bios idle calls are done
> */
> #ifdef CONFIG_APM_CPU_IDLE
> -#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2012
> #define DEFAULT_IDLE_THRESHOLD 95
> #else
> #define DEFAULT_IDLE_THRESHOLD 100
> #endif
> #define DEFAULT_IDLE_PERIOD (100 / 3)
>
> +static int apm_cpu_idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index);
> +
> +static struct cpuidle_driver apm_idle_driver = {
> + .name = "apm_idle",
> + .owner = THIS_MODULE,
> + .en_core_tk_irqen = 1,
> + .states = {
> + { /* entry 0 is for polling */ },
> + { /* entry 1 is for APM idle */
> + .name = "APM",
> + .desc = "APM idle",
> + .flags = CPUIDLE_FLAG_TIME_VALID,
> + .exit_latency = 250, /* WAG */
> + .target_residency = 500, /* WAG */
> + .enter = &apm_cpu_idle
> + },
> + },
> + .state_count = 2,
> +};
> +
> +static struct cpuidle_device apm_cpuidle_device = {
> + .state_count = 2,
> +};
Actually this initialization is not needed because when it is set to
zero, the cpuidle_enable_device function will set it for us from the
driver's state_count.
int cpuidle_enable_device(struct cpuidle_device *dev)
{
...
if (!dev->state_count)
dev->state_count = drv->state_count;
}
It is useful to set a value when it differs from the driver's one.
Otherwise :
Reviewed-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> /*
> * Local variables
> */
> @@ -377,7 +403,6 @@ static struct {
> static int clock_slowed;
> static int idle_threshold __read_mostly = DEFAULT_IDLE_THRESHOLD;
> static int idle_period __read_mostly = DEFAULT_IDLE_PERIOD;
> -static int set_pm_idle;
> static int suspends_pending;
> static int standbys_pending;
> static int ignore_sys_suspend;
> @@ -884,8 +909,6 @@ static void apm_do_busy(void)
> #define IDLE_CALC_LIMIT (HZ * 100)
> #define IDLE_LEAKY_MAX 16
>
> -static void (*original_pm_idle)(void) __read_mostly;
> -
> /**
> * apm_cpu_idle - cpu idling for APM capable Linux
> *
> @@ -894,7 +917,8 @@ static void (*original_pm_idle)(void) __read_mostly;
> * Furthermore it calls the system default idle routine.
> */
>
> -static void apm_cpu_idle(void)
> +static int apm_cpu_idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index)
> {
> static int use_apm_idle; /* = 0 */
> static unsigned int last_jiffies; /* = 0 */
> @@ -904,7 +928,6 @@ static void apm_cpu_idle(void)
> unsigned int jiffies_since_last_check = jiffies - last_jiffies;
> unsigned int bucket;
>
> - WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2012");
> recalc:
> if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
> use_apm_idle = 0;
> @@ -950,10 +973,7 @@ recalc:
> break;
> }
> }
> - if (original_pm_idle)
> - original_pm_idle();
> - else
> - default_idle();
> + default_idle();
> local_irq_disable();
> jiffies_since_last_check = jiffies - last_jiffies;
> if (jiffies_since_last_check > idle_period)
> @@ -963,7 +983,7 @@ recalc:
> if (apm_idle_done)
> apm_do_busy();
>
> - local_irq_enable();
> + return index;
> }
>
> /**
> @@ -2381,9 +2401,9 @@ static int __init apm_init(void)
> if (HZ != 100)
> idle_period = (idle_period * HZ) / 100;
> if (idle_threshold < 100) {
> - original_pm_idle = pm_idle;
> - pm_idle = apm_cpu_idle;
> - set_pm_idle = 1;
> + if (!cpuidle_register_driver(&apm_idle_driver))
> + if (cpuidle_register_device(&apm_cpuidle_device))
> + cpuidle_unregister_driver(&apm_idle_driver);
> }
>
> return 0;
> @@ -2393,15 +2413,9 @@ static void __exit apm_exit(void)
> {
> int error;
>
> - if (set_pm_idle) {
> - pm_idle = original_pm_idle;
> - /*
> - * We are about to unload the current idle thread pm callback
> - * (pm_idle), Wait for all processors to update cached/local
> - * copies of pm_idle before proceeding.
> - */
> - kick_all_cpus_sync();
> - }
> + cpuidle_unregister_device(&apm_cpuidle_device);
> + cpuidle_unregister_driver(&apm_idle_driver);
> +
> if (((apm_info.bios.flags & APM_BIOS_DISENGAGED) == 0)
> && (apm_info.connection_version > 0x0100)) {
> error = apm_engage_power_management(APM_DEVICE_ALL, 0);
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 2ed787f..f571a6e 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -272,9 +272,6 @@ EXPORT_SYMBOL(boot_option_idle_override);
> * Powermanagement idle function, if any..
> */
> void (*pm_idle)(void);
> -#ifdef CONFIG_APM_MODULE
> -EXPORT_SYMBOL(pm_idle);
> -#endif
>
> #ifndef CONFIG_SMP
> static inline void play_dead(void)
>
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