Re: [PATCH v6 3/6] thermal: Add generic power domain warming device driver.
From: Lukasz Luba
Date: Tue Jul 07 2020 - 06:58:45 EST
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__ */