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SubjectRe: [PATCH v6 3/6] thermal: Add generic power domain warming device driver.
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Hi Daniel and Thara

On 7/3/20 11:02 AM, Daniel Lezcano wrote:
>
> Hi Thara,
>
> sorry for the delay.
>
> Added Lukasz.

Thank you for adding me.
I will go through the patches to understand them and build
the context. I can see some interesting idea described below.

Regards,
Lukasz

>
> On 04/06/2020 03:53, Thara Gopinath wrote:
>> Resources modeled as power domains in linux kernel can be used to warm the
>> SoC(eg. mx power domain on sdm845). To support this feature, introduce a
>> generic power domain warming device driver that can be plugged into the
>> thermal framework (The thermal framework itself requires further
>> modifiction to support a warming device in place of a cooling device.
>> Those extensions are not introduced in this patch series).
>
> The patch itself looks fine but I'm not very convinced about using a
> specific driver as a warming device.
>
> It is all about changing the performance state of a device and the power
> domain is a way to access the associated callback.
>
> It could be used as a cooling device as well.
>
> The cpufreq cooling device could be used as a warming device and the way
> we access the performance state is the freq qos.
>
> We end up with different ways to do the same thing : change the
> performance state.
>
> On the other side, the energy model is being moved to the struct device,
> so we will have gpu and cpu using it to retrieve a performance state
> given a power value.
>
> My opinion is instead of multiplying the ways to do the same think, we
> should find a way to unify all the passive cooling devices into a single
> generic performance state based mitigation device.
>
> It does not imply to make all the passive cooling device changes but
> provide a generic one first.
>
> The ideal would be to register a struct device as a performance state
> capable device and use the energy model stored in it.
>
> In the meantime, the energy model should embed a couple of callbacks
> get_power / set_power to set the performance state.
>
> That implies a bit of more work, but IMHO it is worth to do.
>
> Does it make sense ?
>
>
>> ---
>>
>> v3->v4:
>> - Removed late_init hook pd_warming_device_ops.
>> - Use of_genpd_add_device instead of pm_genpd_add_device to attach
>> device to the generic power domain.
>> - Use thermal_of_cooling_device_parent_register to register the
>> cooling device so that the device with genpd attached can be
>> made parent of the cooling device.
>> - With above changes, remove reference to generic_pm_domain in
>> pd_warming_device.
>>
>> v4->v5:
>> - All the below changes are as per Ulf's review comments.
>> - Renamed pwr_domain_warming.c and pwr_domain_warming.h to
>> pd_warming.c and pd_warming.h.
>> - Renamed pwr_domain_warming_register API to
>> of_pd_warming_register.
>> - Dropped in-param pd_name to of_pd_warming_register.
>> - Introduced ID allocator to uniquely identify each power domain
>> warming device.
>> - Introduced pd_warming_release to handle device kfree for
>> pd_warming_device.
>> - Introduced pm_genpd_remove_device in the error exit path
>> of of_pd_warming_register.
>> v5->v6:
>> - Fixed issues with ->release() and kfree(dev) as pointed
>> out by Ulf.
>>
>> drivers/thermal/Kconfig | 10 +++
>> drivers/thermal/Makefile | 4 +
>> drivers/thermal/pd_warming.c | 169 +++++++++++++++++++++++++++++++++++
>> include/linux/pd_warming.h | 29 ++++++
>> 4 files changed, 212 insertions(+)
>> create mode 100644 drivers/thermal/pd_warming.c
>> create mode 100644 include/linux/pd_warming.h
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index e53314ea9e25..3a0bcf3e8bd9 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -206,6 +206,16 @@ config DEVFREQ_THERMAL
>>
>> If you want this support, you should say Y here.
>>
>> +config PWR_DOMAIN_WARMING_THERMAL
>> + bool "Power Domain based warming device"
>> + depends on PM_GENERIC_DOMAINS_OF
>> + help
>> + This implements the generic power domain based warming
>> + mechanism through increasing the performance state of
>> + a power domain.
>> +
>> + If you want this support, you should say Y here.
>> +
>> config THERMAL_EMULATION
>> bool "Thermal emulation mode support"
>> help
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 86c506410cc0..14fa696a08bd 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -28,7 +28,11 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL) += clock_cooling.o
>> # devfreq cooling
>> thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
>>
>> +#pwr domain warming
>> +thermal_sys-$(CONFIG_PWR_DOMAIN_WARMING_THERMAL) += pd_warming.o
>> +
>> obj-$(CONFIG_K3_THERMAL) += k3_bandgap.o
>> +
>> # platform thermal drivers
>> obj-y += broadcom/
>> obj-$(CONFIG_THERMAL_MMIO) += thermal_mmio.o
>> diff --git a/drivers/thermal/pd_warming.c b/drivers/thermal/pd_warming.c
>> new file mode 100644
>> index 000000000000..1ea93481c79b
>> --- /dev/null
>> +++ b/drivers/thermal/pd_warming.c
>> @@ -0,0 +1,169 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2019, Linaro Ltd
>> + */
>> +#include <linux/err.h>
>> +#include <linux/kernel.h>
>> +#include <linux/init.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/module.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/slab.h>
>> +#include <linux/pd_warming.h>
>> +
>> +struct pd_warming_device {
>> + struct thermal_cooling_device *cdev;
>> + struct device dev;
>> + int id;
>> + int max_state;
>> + int cur_state;
>> + bool runtime_resumed;
>> +};
>> +
>> +static DEFINE_IDA(pd_ida);
>> +
>> +static int pd_wdev_get_max_state(struct thermal_cooling_device *cdev,
>> + unsigned long *state)
>> +{
>> + struct pd_warming_device *pd_wdev = cdev->devdata;
>> +
>> + *state = pd_wdev->max_state;
>> + return 0;
>> +}
>> +
>> +static int pd_wdev_get_cur_state(struct thermal_cooling_device *cdev,
>> + unsigned long *state)
>> +{
>> + struct pd_warming_device *pd_wdev = cdev->devdata;
>> +
>> + *state = dev_pm_genpd_get_performance_state(&pd_wdev->dev);
>> +
>> + return 0;
>> +}
>> +
>> +static int pd_wdev_set_cur_state(struct thermal_cooling_device *cdev,
>> + unsigned long state)
>> +{
>> + struct pd_warming_device *pd_wdev = cdev->devdata;
>> + struct device *dev = &pd_wdev->dev;
>> + int ret;
>> +
>> + ret = dev_pm_genpd_set_performance_state(dev, state);
>> +
>> + if (ret)
>> + return ret;
>> +
>> + if (state && !pd_wdev->runtime_resumed) {
>> + ret = pm_runtime_get_sync(dev);
>> + pd_wdev->runtime_resumed = true;
>> + } else if (!state && pd_wdev->runtime_resumed) {
>> + ret = pm_runtime_put(dev);
>> + pd_wdev->runtime_resumed = false;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static struct thermal_cooling_device_ops pd_warming_device_ops = {
>> + .get_max_state = pd_wdev_get_max_state,
>> + .get_cur_state = pd_wdev_get_cur_state,
>> + .set_cur_state = pd_wdev_set_cur_state,
>> +};
>> +
>> +static void pd_warming_release(struct device *dev)
>> +{
>> + struct pd_warming_device *pd_wdev;
>> +
>> + pd_wdev = container_of(dev, struct pd_warming_device, dev);
>> + kfree(pd_wdev);
>> +}
>> +
>> +struct thermal_cooling_device *
>> +of_pd_warming_register(struct device *parent, int pd_id)
>> +{
>> + struct pd_warming_device *pd_wdev;
>> + struct of_phandle_args pd_args;
>> + char cdev_name[THERMAL_NAME_LENGTH];
>> + int ret;
>> +
>> + pd_wdev = kzalloc(sizeof(*pd_wdev), GFP_KERNEL);
>> + if (!pd_wdev)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + dev_set_name(&pd_wdev->dev, "%s_%d_warming_dev",
>> + dev_name(parent), pd_id);
>> + pd_wdev->dev.parent = parent;
>> + pd_wdev->dev.release = pd_warming_release;
>> +
>> + ret = device_register(&pd_wdev->dev);
>> + if (ret) {
>> + put_device(&pd_wdev->dev);
>> + goto out;
>> + }
>> +
>> + ret = ida_simple_get(&pd_ida, 0, 0, GFP_KERNEL);
>> + if (ret < 0)
>> + goto unregister_device;
>> +
>> + pd_wdev->id = ret;
>> +
>> + pd_args.np = parent->of_node;
>> + pd_args.args[0] = pd_id;
>> + pd_args.args_count = 1;
>> +
>> + ret = of_genpd_add_device(&pd_args, &pd_wdev->dev);
>> +
>> + if (ret)
>> + goto remove_ida;
>> +
>> + ret = dev_pm_genpd_performance_state_count(&pd_wdev->dev);
>> + if (ret < 0)
>> + goto out_genpd;
>> +
>> + pd_wdev->max_state = ret - 1;
>> + pm_runtime_enable(&pd_wdev->dev);
>> + pd_wdev->runtime_resumed = false;
>> +
>> + snprintf(cdev_name, sizeof(cdev_name), "thermal-pd-%d", pd_wdev->id);
>> + pd_wdev->cdev = thermal_of_cooling_device_register
>> + (NULL, cdev_name, pd_wdev,
>> + &pd_warming_device_ops);
>> + if (IS_ERR(pd_wdev->cdev)) {
>> + pr_err("unable to register %s cooling device\n", cdev_name);
>> + ret = PTR_ERR(pd_wdev->cdev);
>> + goto out_runtime_disable;
>> + }
>> +
>> + return pd_wdev->cdev;
>> +
>> +out_runtime_disable:
>> + pm_runtime_disable(&pd_wdev->dev);
>> +out_genpd:
>> + pm_genpd_remove_device(&pd_wdev->dev);
>> +remove_ida:
>> + ida_simple_remove(&pd_ida, pd_wdev->id);
>> +unregister_device:
>> + device_unregister(&pd_wdev->dev);
>> +out:
>> + return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL_GPL(of_pd_warming_register);
>> +
>> +void pd_warming_unregister(struct thermal_cooling_device *cdev)
>> +{
>> + struct pd_warming_device *pd_wdev = cdev->devdata;
>> + struct device *dev = &pd_wdev->dev;
>> +
>> + if (pd_wdev->runtime_resumed) {
>> + dev_pm_genpd_set_performance_state(dev, 0);
>> + pm_runtime_put(dev);
>> + pd_wdev->runtime_resumed = false;
>> + }
>> + pm_runtime_disable(dev);
>> + pm_genpd_remove_device(dev);
>> + ida_simple_remove(&pd_ida, pd_wdev->id);
>> + thermal_cooling_device_unregister(cdev);
>> + device_unregister(dev);
>> +}
>> +EXPORT_SYMBOL_GPL(pd_warming_unregister);
>> diff --git a/include/linux/pd_warming.h b/include/linux/pd_warming.h
>> new file mode 100644
>> index 000000000000..550a5683b56d
>> --- /dev/null
>> +++ b/include/linux/pd_warming.h
>> @@ -0,0 +1,29 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2019, Linaro Ltd.
>> + */
>> +#ifndef __PWR_DOMAIN_WARMING_H__
>> +#define __PWR_DOMAIN_WARMING_H__
>> +
>> +#include <linux/pm_domain.h>
>> +#include <linux/thermal.h>
>> +
>> +#ifdef CONFIG_PWR_DOMAIN_WARMING_THERMAL
>> +struct thermal_cooling_device *
>> +of_pd_warming_register(struct device *parent, int pd_id);
>> +
>> +void pd_warming_unregister(struct thermal_cooling_device *cdev);
>> +
>> +#else
>> +static inline struct thermal_cooling_device *
>> +of_pd_warming_register(struct device *parent, int pd_id)
>> +{
>> + return ERR_PTR(-ENOSYS);
>> +}
>> +
>> +static inline void
>> +pd_warming_unregister(struct thermal_cooling_device *cdev)
>> +{
>> +}
>> +#endif /* CONFIG_PWR_DOMAIN_WARMING_THERMAL */
>> +#endif /* __PWR_DOMAIN_WARMING_H__ */
>>
>
>

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