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Date: Sun, 09 Nov 2014 16:57:51 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Kukjin Kim <kgene.kim@...sung.com>
CC: Tomasz Figa <tomasz.figa@...il.com>,
Colin Cross <ccross@...gle.com>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH 2/2] cpuidle: exynos: add coupled cpuidle support for
Exynos4210
On 11/07/2014 07:00 PM, Bartlomiej Zolnierkiewicz wrote:
> The following patch adds coupled cpuidle support for Exynos4210 to
> an existing cpuidle-exynos driver. As a result it enables AFTR mode
> to be used by default on Exynos4210 without the need to hot unplug
> CPU1 first.
>
> The patch is heavily based on earlier cpuidle-exynos4210 driver from
> Daniel Lezcano:
>
> http://www.spinics.net/lists/linux-samsung-soc/msg28134.html
>
> Changes from Daniel's code include:
> - porting code to current kernels
> - fixing it to work on my setup (by using S5P_INFORM register
> instead of S5P_VA_SYSRAM one on Revison 1.1 and retrying poking
> CPU1 out of the BOOT ROM if necessary)
> - fixing rare lockup caused by waiting for CPU1 to get stuck in
> the BOOT ROM (CPU hotplug code in arch/arm/mach-exynos/platsmp.c
> doesn't require this and works fine)
> - moving Exynos specific code to arch/arm/mach-exynos/pm.c
> - using cpu_boot_reg_base() helper instead of BOOT_VECTOR macro
> - using exynos_cpu_*() helpers instead of accessing registers
> directly
> - using arch_send_wakeup_ipi_mask() instead of dsb_sev()
> (this matches CPU hotplug code in arch/arm/mach-exynos/platsmp.c)
I am curious. You experienced very rare hangs after running the tests a
few hours, right ? Is the SEV replaced by the IPI solving the issue ? If
yes, how did you catch it ?
>- integrating separate exynos4210-cpuidle driver into existing
> exynos-cpuidle one
>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Colin Cross <ccross@...gle.com>
> Cc: Kukjin Kim <kgene.kim@...sung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Cc: Tomasz Figa <tomasz.figa@...il.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
A few comments below:
> Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
> arch/arm/mach-exynos/common.h | 4 +
> arch/arm/mach-exynos/exynos.c | 4 +
> arch/arm/mach-exynos/platsmp.c | 2 +-
> arch/arm/mach-exynos/pm.c | 122 +++++++++++++++++++++++++++
> drivers/cpuidle/Kconfig.arm | 1 +
> drivers/cpuidle/cpuidle-exynos.c | 62 ++++++++++++--
> include/linux/platform_data/cpuidle-exynos.h | 20 +++++
> 7 files changed, 209 insertions(+), 6 deletions(-)
> create mode 100644 include/linux/platform_data/cpuidle-exynos.h
>
> diff --git a/arch/arm/mach-exynos/common.h b/arch/arm/mach-exynos/common.h
> index d4d09bc..f208a60 100644
> --- a/arch/arm/mach-exynos/common.h
> +++ b/arch/arm/mach-exynos/common.h
> @@ -14,6 +14,7 @@
>
> #include <linux/reboot.h>
> #include <linux/of.h>
> +#include <linux/platform_data/cpuidle-exynos.h>
>
> #define EXYNOS3250_SOC_ID 0xE3472000
> #define EXYNOS3_SOC_MASK 0xFFFFF000
> @@ -168,8 +169,11 @@ extern void exynos_pm_central_suspend(void);
> extern int exynos_pm_central_resume(void);
> extern void exynos_enter_aftr(void);
>
> +extern struct cpuidle_exynos_data cpuidle_coupled_exynos_data;
> +
> extern void s5p_init_cpu(void __iomem *cpuid_addr);
> extern unsigned int samsung_rev(void);
> +extern void __iomem *cpu_boot_reg_base(void);
>
> static inline void pmu_raw_writel(u32 val, u32 offset)
> {
> diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
> index a487e59..4f4eb9e 100644
> --- a/arch/arm/mach-exynos/exynos.c
> +++ b/arch/arm/mach-exynos/exynos.c
> @@ -317,6 +317,10 @@ static void __init exynos_dt_machine_init(void)
> if (!IS_ENABLED(CONFIG_SMP))
> exynos_sysram_init();
>
> +#ifdef CONFIG_ARM_EXYNOS_CPUIDLE
> + if (of_machine_is_compatible("samsung,exynos4210"))
> + exynos_cpuidle.dev.platform_data = &cpuidle_coupled_exynos_data;
> +#endif
You should not add those #ifdef.
> if (of_machine_is_compatible("samsung,exynos4210") ||
> of_machine_is_compatible("samsung,exynos4212") ||
> (of_machine_is_compatible("samsung,exynos4412") &&
> diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
> index adb36a8..0e3ffc9 100644
> --- a/arch/arm/mach-exynos/platsmp.c
> +++ b/arch/arm/mach-exynos/platsmp.c
> @@ -182,7 +182,7 @@ int exynos_cluster_power_state(int cluster)
> S5P_CORE_LOCAL_PWR_EN);
> }
>
> -static inline void __iomem *cpu_boot_reg_base(void)
> +void __iomem *cpu_boot_reg_base(void)
> {
> if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
> return pmu_base_addr + S5P_INFORM5;
> diff --git a/arch/arm/mach-exynos/pm.c b/arch/arm/mach-exynos/pm.c
> index 4b36ab5..44cc08a 100644
> --- a/arch/arm/mach-exynos/pm.c
> +++ b/arch/arm/mach-exynos/pm.c
> @@ -178,3 +178,125 @@ void exynos_enter_aftr(void)
>
> cpu_pm_exit();
> }
> +
> +static atomic_t cpu1_wakeup = ATOMIC_INIT(0);
> +
> +static int exynos_cpu0_enter_aftr(void)
> +{
> + int ret = -1;
> +
> + /*
> + * If the other cpu is powered on, we have to power it off, because
> + * the AFTR state won't work otherwise
> + */
> + if (cpu_online(1)) {
> + /*
> + * We reach a sync point with the coupled idle state, we know
> + * the other cpu will power down itself or will abort the
> + * sequence, let's wait for one of these to happen
> + */
> + while (exynos_cpu_power_state(1)) {
> + /*
> + * The other cpu may skip idle and boot back
> + * up again
> + */
> + if (atomic_read(&cpu1_wakeup))
> + goto abort;
> +
> + /*
> + * The other cpu may bounce through idle and
> + * boot back up again, getting stuck in the
> + * boot rom code
> + */
> + if (__raw_readl(cpu_boot_reg_base()) == 0)
> + goto abort;
> +
> + cpu_relax();
> + }
> + }
> +
> + exynos_enter_aftr();
> + ret = 0;
> +
> +abort:
> + if (cpu_online(1)) {
> + /*
> + * Set the boot vector to something non-zero
> + */
> + __raw_writel(virt_to_phys(exynos_cpu_resume),
> + cpu_boot_reg_base());
> + dsb();
> +
> + /*
> + * Turn on cpu1 and wait for it to be on
> + */
> + exynos_cpu_power_up(1);
> + while (exynos_cpu_power_state(1) != S5P_CORE_LOCAL_PWR_EN)
> + cpu_relax();
> +
> + while (!atomic_read(&cpu1_wakeup)) {
> + /*
> + * Poke cpu1 out of the boot rom
> + */
> + __raw_writel(virt_to_phys(exynos_cpu_resume),
> + cpu_boot_reg_base());
> +
> + arch_send_wakeup_ipi_mask(cpumask_of(1));
> + }
> + }
> +
> + return ret;
> +}
> +
> +static int exynos_wfi_finisher(unsigned long flags)
> +{
> + cpu_do_idle();
> +
> + return -1;
> +}
> +
> +static int exynos_cpu1_powerdown(void)
> +{
> + int ret = -1;
> +
> + /*
> + * Idle sequence for cpu1
> + */
> + if (cpu_pm_enter())
> + goto cpu1_aborted;
> +
> + /*
> + * Turn off cpu 1
> + */
> + exynos_cpu_power_down(1);
> +
> + ret = cpu_suspend(0, exynos_wfi_finisher);
> +
> + cpu_pm_exit();
> +
> +cpu1_aborted:
> + dsb();
> + /*
> + * Notify cpu 0 that cpu 1 is awake
> + */
> + atomic_set(&cpu1_wakeup, 1);
> +
> + return ret;
> +}
> +
> +static void exynos_pre_enter_aftr(void)
> +{
> + __raw_writel(virt_to_phys(exynos_cpu_resume), cpu_boot_reg_base());
> +}
> +
> +static void exynos_post_enter_aftr(void)
> +{
> + atomic_set(&cpu1_wakeup, 0);
> +}
> +
> +struct cpuidle_exynos_data cpuidle_coupled_exynos_data = {
> + .cpu0_enter_aftr = exynos_cpu0_enter_aftr,
> + .cpu1_powerdown = exynos_cpu1_powerdown,
> + .pre_enter_aftr = exynos_pre_enter_aftr,
> + .post_enter_aftr = exynos_post_enter_aftr,
> +};
> diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
> index 8c16ab2..8e07c94 100644
> --- a/drivers/cpuidle/Kconfig.arm
> +++ b/drivers/cpuidle/Kconfig.arm
> @@ -55,6 +55,7 @@ config ARM_AT91_CPUIDLE
> config ARM_EXYNOS_CPUIDLE
> bool "Cpu Idle Driver for the Exynos processors"
> depends on ARCH_EXYNOS
> + select ARCH_NEEDS_CPU_IDLE_COUPLED if SMP
> help
> Select this to enable cpuidle for Exynos processors
>
> diff --git a/drivers/cpuidle/cpuidle-exynos.c b/drivers/cpuidle/cpuidle-exynos.c
> index ba9b34b..4700d5d 100644
> --- a/drivers/cpuidle/cpuidle-exynos.c
> +++ b/drivers/cpuidle/cpuidle-exynos.c
> @@ -1,8 +1,11 @@
> -/* linux/arch/arm/mach-exynos/cpuidle.c
> - *
> - * Copyright (c) 2011 Samsung Electronics Co., Ltd.
> +/*
> + * Copyright (c) 2011-2014 Samsung Electronics Co., Ltd.
> * http://www.samsung.com
> *
> + * Coupled cpuidle support based on the work of:
> + * Colin Cross <ccross@...roid.com>
> + * Daniel Lezcano <daniel.lezcano@...aro.org>
> + *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> * published by the Free Software Foundation.
> @@ -13,13 +16,49 @@
> #include <linux/export.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/platform_data/cpuidle-exynos.h>
>
> #include <asm/proc-fns.h>
> #include <asm/suspend.h>
> #include <asm/cpuidle.h>
>
> +static atomic_t exynos_idle_barrier;
> +
> +static struct cpuidle_exynos_data *exynos_cpuidle_pdata;
> static void (*exynos_enter_aftr)(void);
>
> +static int exynos_enter_coupled_lowpower(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> +{
> + int ret;
> +
> + exynos_cpuidle_pdata->pre_enter_aftr();
> +
> + /*
> + * Waiting all cpus to reach this point at the same moment
> + */
> + cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
> +
> + /*
> + * Both cpus will reach this point at the same time
> + */
> + ret = dev->cpu ? exynos_cpuidle_pdata->cpu1_powerdown()
> + : exynos_cpuidle_pdata->cpu0_enter_aftr();
> + if (ret)
> + index = ret;
> +
> + /*
> + * Waiting all cpus to finish the power sequence before going further
> + */
> + cpuidle_coupled_parallel_barrier(dev, &exynos_idle_barrier);
> +
> + exynos_cpuidle_pdata->post_enter_aftr();
> +
> + return index;
> +}
> +
> static int exynos_enter_lowpower(struct cpuidle_device *dev,
> struct cpuidle_driver *drv,
> int index)
> @@ -58,11 +97,24 @@ static struct cpuidle_driver exynos_idle_driver = {
>
> static int exynos_cpuidle_probe(struct platform_device *pdev)
> {
> + const struct cpumask *coupled_cpus = NULL;
> int ret;
>
> - exynos_enter_aftr = (void *)(pdev->dev.platform_data);
> + if (of_machine_is_compatible("samsung,exynos4210")) {
> + exynos_cpuidle_pdata = pdev->dev.platform_data;
> +
> + exynos_idle_driver.states[1].enter =
> + exynos_enter_coupled_lowpower;
> + exynos_idle_driver.states[1].exit_latency = 5000;
> + exynos_idle_driver.states[1].target_residency = 10000;
> + exynos_idle_driver.states[1].flags |= CPUIDLE_FLAG_COUPLED |
> + CPUIDLE_FLAG_TIMER_STOP;
I tried to remove those dynamic state allocation everywhere in the
different drivers. I would prefer to have another cpuidle_driver to be
registered with its states instead of overwriting the existing idle state.
struct cpuidle_driver exynos4210_idle_driver = {
.name = "exynos4210_idle",
.owner = THIS_MODULE,
.states = {
[0] = ARM_CPUIDLE_WFI_STATE,
[1] = {
.enter = exynos_enter_coupled_lowpower,
.exit_latency = 5000,
.target_residency = 10000,
.flags = CPUIDLE_FLAG_TIME_VALID |
CPUIDLE_FLAG_COUPLED |
CPUIDLE_FLAG_TIMER_STOP,
.name = "C1",
.desc = "ARM power down",
},
}
};
and then:
if (of_machine_is_compatible("samsung,exynos4210")) {
...
ret = cpuidle_register(&exynos4210_idle_driver,
cpu_online_mask);
...
}
...
If we can reuse this mechanism, which I believe it is possible to, for
4420 and 5250. Then we will be able to refactor this out again.
> +
> + coupled_cpus = cpu_possible_mask;
> + } else
> + exynos_enter_aftr = (void *)(pdev->dev.platform_data);
>
> - ret = cpuidle_register(&exynos_idle_driver, NULL);
> + ret = cpuidle_register(&exynos_idle_driver, coupled_cpus);
> if (ret) {
> dev_err(&pdev->dev, "failed to register cpuidle driver\n");
> return ret;
> diff --git a/include/linux/platform_data/cpuidle-exynos.h b/include/linux/platform_data/cpuidle-exynos.h
> new file mode 100644
> index 0000000..bfa40e4
> --- /dev/null
> +++ b/include/linux/platform_data/cpuidle-exynos.h
> @@ -0,0 +1,20 @@
> +/*
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * http://www.samsung.com
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> +*/
> +
> +#ifndef __CPUIDLE_EXYNOS_H
> +#define __CPUIDLE_EXYNOS_H
> +
> +struct cpuidle_exynos_data {
> + int (*cpu0_enter_aftr)(void);
> + int (*cpu1_powerdown)(void);
> + void (*pre_enter_aftr)(void);
> + void (*post_enter_aftr)(void);
> +};
> +
> +#endif
>
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