Re: [PATCH v4 7/8] qcom: cpuidle: Add cpuidle driver for QCOM cpus

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 08/20/2014 12:15 AM, Lina Iyer wrote:
> Add cpuidle driver interface to allow cpus to go into C-States.
> Use the cpuidle DT interfacecommon across ARM architectures to provide

                          ^^^^^^^^

> the C-State information to the cpuidle framework.
>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> ---
>   drivers/cpuidle/Kconfig.arm    |   7 +++
>   drivers/cpuidle/Makefile       |   1 +
>   drivers/cpuidle/cpuidle-qcom.c | 119 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 127 insertions(+)
>   create mode 100644 drivers/cpuidle/cpuidle-qcom.c
>
> diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
> index e339c7f..26e31bd 100644
> --- a/drivers/cpuidle/Kconfig.arm
> +++ b/drivers/cpuidle/Kconfig.arm
> @@ -63,3 +63,10 @@ config ARM_MVEBU_V7_CPUIDLE
>   	depends on ARCH_MVEBU
>   	help
>   	  Select this to enable cpuidle on Armada 370, 38x and XP processors.
> +
> +config ARM_QCOM_CPUIDLE
> +	bool "CPU Idle drivers for Qualcomm processors"
> +	depends on QCOM_PM
> +	select DT_IDLE_STATES
> +	help
> +	  Select this to enable cpuidle for QCOM processors
> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> index 4d177b9..6c222d5 100644
> --- a/drivers/cpuidle/Makefile
> +++ b/drivers/cpuidle/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_ARM_ZYNQ_CPUIDLE)		+= cpuidle-zynq.o
>   obj-$(CONFIG_ARM_U8500_CPUIDLE)         += cpuidle-ux500.o
>   obj-$(CONFIG_ARM_AT91_CPUIDLE)          += cpuidle-at91.o
>   obj-$(CONFIG_ARM_EXYNOS_CPUIDLE)        += cpuidle-exynos.o
> +obj-$(CONFIG_ARM_QCOM_CPUIDLE)		+= cpuidle-qcom.o
>
>   ###############################################################################
>   # MIPS drivers
> diff --git a/drivers/cpuidle/cpuidle-qcom.c b/drivers/cpuidle/cpuidle-qcom.c
> new file mode 100644
> index 0000000..4aae672
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-qcom.c
> @@ -0,0 +1,119 @@
> +/* Copyright (c) 2014, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2014, Linaro Limited.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/cpuidle.h>
> +#include <linux/cpumask.h>
> +#include <linux/slab.h>

See below, cpumask is not needed, you can remove slab.h and cpumask.h.

> +#include <linux/of_device.h>
> +
> +#include <soc/qcom/pm.h>
> +#include "dt_idle_states.h"
> +
> +static enum msm_pm_sleep_mode modes[CPUIDLE_STATE_MAX];
> +
> +static int qcom_lpm_enter(struct cpuidle_device *dev,
> +				struct cpuidle_driver *drv, int index)
> +{
> +	return msm_cpu_pm_enter_sleep(modes[index], true);

You should return the index here.

> +}
> +
> +static struct cpuidle_driver qcom_cpuidle_driver = {
> +	.name	= "qcom_cpuidle",
> +	.owner	= THIS_MODULE,
> +};
> +
> +static void parse_state_translations(struct cpuidle_driver *drv)
> +{
> +	struct device_node *state_node, *cpu_node;
> +	const char *mode_name;
> +	int i, j;
> +
> +	struct name_map {
> +		enum msm_pm_sleep_mode mode;
> +		char *name;
> +	};
> +	static struct name_map c_states[] = {
> +		{ MSM_PM_SLEEP_MODE_POWER_COLLAPSE_STANDALONE,
> +						"standalone-pc" },

What is standalone-pc and collapse ? Core power down ?

> +		{ MSM_PM_SLEEP_MODE_WAIT_FOR_INTERRUPT, "wfi" },
> +	};
> +
> +	cpu_node = of_cpu_device_node_get(cpumask_first(drv->cpumask));
> +	if (!cpu_node)
> +		return;
> +
> +	/**
> +	 * Get the state description from idle-state node entry-method
> +	 * First state is always WFI, per spec.
> +	 */
> +	modes[0] = MSM_PM_SLEEP_MODE_WAIT_FOR_INTERRUPT;
> +	for (i = 1; i < drv->state_count; i++) {
> +		mode_name = NULL;
> +		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
> +		of_property_read_string(state_node, "entry-method",
> +						&mode_name);
> +		for (j = 0; mode_name && (j < ARRAY_SIZE(c_states)); j++) {
> +			if (!strcmp(mode_name, c_states[j].name)) {
> +				modes[i] = c_states[j].mode;
> +				break;
> +			}
> +		}
> +	}
> +}

For the function above, I believe we can do better with the idle_dt_init 
function to prevent to have to reparse the infos.

I had the opportunity to discuss with Lorenzo privately and we found a 
solution he will submit to solve that.

> +static int qcom_cpuidle_init(void)
> +{
> +	struct cpuidle_driver *drv = &qcom_cpuidle_driver;
> +	int ret;
> +	int i;
> +
> +	drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
> +	if (!drv->cpumask)
> +		return -ENOMEM;
> +	cpumask_copy(drv->cpumask, cpu_possible_mask);

You can get rid of this because the driver does not rely on the multiple 
driver support. If the drv->cpumask is NULL it will be automatically set 
to cpu_possible_mask by the cpuidle framework.

> +
> +	/**
> +	 * Default to standard for WFI (index = 0)
> +	 * Probe only for other states
> +	 */
> +	ret = dt_init_idle_driver(drv, 1);

So IIUC, if you specify the index 1, that means the state[0] will be the 
default WFI. But you override the callback below in the loop.

I recommend you use the default arm wfi callback but you implement the 
cpu_do_idle for your platform.

> +	if (ret < 0) {
> +		pr_err("%s: failed to initialize idle states\n", __func__);
> +		goto failed;
> +	}
> +
> +	/* Parse the idle states for C-States on this cpu */
> +	parse_state_translations(drv);
> +
> +	/* Register entry point for all low states */
> +	for (i = 0; i < drv->state_count; i++)
> +		drv->states[i].enter = qcom_lpm_enter;
> +	drv->safe_state_index = 0;

The safe_state index is only used for the couple c-states and as the 
driver is statically defined, it is pointless to initialize this variable.

> +
> +	ret = cpuidle_register(drv, NULL);
> +	if (ret) {
> +		pr_err("%s: failed to register cpuidle driver\n", __func__);
> +		goto failed;
> +	}
> +
> +	return 0;
> +
> +failed:
> +	kfree(drv->cpumask);
> +	return ret;
> +}
> +module_init(qcom_cpuidle_init);

Can you stick to the platform_driver paradigm like the other drivers ?

Thanks
   -- Daniel

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