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@linaro.org Cc: Colin Cross ccross@google.com Cc: Kukjin Kim kgene.kim@samsung.com Cc: Krzysztof Kozlowski k.kozlowski@samsung.com Cc: Tomasz Figa tomasz.figa@gmail.com Signed-off-by: Bartlomiej Zolnierkiewicz b.zolnierkie@samsung.com

Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org

A few comments below:

Acked-by: Kyungmin Park kyungmin.park@samsung.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@android.com
• • Daniel Lezcano daniel.lezcano@linaro.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