Re: [PATCH v2] ACPI: Split out processor thermal register from ACPI PSS

[Riwen Lu]

在 2022/6/16 22:56, Punit Agrawal 写道:
> Hi Riwen,
>
> Usually it's a good practice to Cc anybody who has commented on previous
> versions. It makes it easier to follow your updates.
Hi Punit,

Sorry. I wanted to Cc to you, but I forgot it. I'll make the patch a v3 
version and Cc you.

Thanks!
> A couple of comments below.
>
> Riwen Lu <luriwen@xxxxxxxxxxx> writes:
>
> > From: Riwen Lu <luriwen@xxxxxxxxxx>
> >
> > Commit 239708a3af44 ("ACPI: Split out ACPI PSS from ACPI Processor
> > driver"), moves processor thermal registration to acpi_pss_perf_init(),
> > which doesn't get executed if ACPI_CPU_FREQ_PSS is not enabled.
> >
> > As ARM64 supports P-states using CPPC, it should be possible to also
> > support processor passive cooling even if PSS is not enabled. Split
> > out the processor thermal cooling register from ACPI PSS to support
> > this, and move it into a separate function in processor_thermal.c.
> >
> > Signed-off-by: Riwen Lu <luriwen@xxxxxxxxxx>
> > ---
> >   drivers/acpi/Kconfig             |  2 +-
> >   drivers/acpi/Makefile            |  5 +--
> >   drivers/acpi/processor_driver.c  | 72 ++++----------------------------
> >   drivers/acpi/processor_thermal.c | 69 ++++++++++++++++++++++++++++++
> >   include/acpi/processor.h         |  6 ++-
> >   5 files changed, 84 insertions(+), 70 deletions(-)
>
> [...]
>
> > --- a/drivers/acpi/processor_driver.c
> > +++ b/drivers/acpi/processor_driver.c
>
> [...]
>
> > @@ -239,7 +183,7 @@ static int __acpi_processor_start(struct acpi_device *device)
> >   		return 0;
> >   
> >   	result = -ENODEV;
> > -	acpi_pss_perf_exit(pr, device);
> > +	acpi_processor_thermal_exit(pr);
> >   
> >   err_power_exit:
> >   	acpi_processor_power_exit(pr);
> > @@ -277,10 +221,10 @@ static int acpi_processor_stop(struct device *dev)
> >   		return 0;
> >   	acpi_processor_power_exit(pr);
> >   
> > -	acpi_pss_perf_exit(pr, device);
> > -
> >   	acpi_cppc_processor_exit(pr);
> >   
> > +	acpi_processor_thermal_exit(pr);
> > +
> >   	return 0;
> >   }
> >   
> > diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
> > index d8b2dfcd59b5..93928db2ae5f 100644
> > --- a/drivers/acpi/processor_thermal.c
> > +++ b/drivers/acpi/processor_thermal.c
> > @@ -266,3 +266,72 @@ const struct thermal_cooling_device_ops processor_cooling_ops = {
> >   	.get_cur_state = processor_get_cur_state,
> >   	.set_cur_state = processor_set_cur_state,
> >   };
> > +
> > +int acpi_processor_thermal_init(struct acpi_processor *pr)
> > +{
> > +	struct acpi_device *device;
> > +	int result = 0;
> > +
> > +	if (!pr)
> > +		return -ENODEV;
>
> What's the reason for this check? When will "pr" be NULL in this code
> path?
I was thinking the function might be called somewhere else. It seems to 
be meaningless.
> > +
> > +	device = acpi_fetch_acpi_dev(pr->handle);
> > +	if (!device)
> > +		return -ENODEV;
>
> Wouldn't it be better to pass the acpi_device into the function as well?
> The device is already available in the caller and it'll avoid having to
> convert it back.
The same reason as above, and I'll modify it.
> > +
> > +	pr->cdev = thermal_cooling_device_register("Processor", device,
> > +						   &processor_cooling_ops);
> > +	if (IS_ERR(pr->cdev)) {
> > +		result = PTR_ERR(pr->cdev);
> > +		return result;
> > +	}
> > +
> > +	dev_dbg(&device->dev, "registered as cooling_device%d\n",
> > +		pr->cdev->id);
> > +
> > +	result = sysfs_create_link(&device->dev.kobj,
> > +				   &pr->cdev->device.kobj,
> > +				   "thermal_cooling");
> > +	if (result) {
> > +		dev_err(&device->dev,
> > +			"Failed to create sysfs link 'thermal_cooling'\n");
> > +		goto err_thermal_unregister;
> > +	}
> > +
> > +	result = sysfs_create_link(&pr->cdev->device.kobj,
> > +				   &device->dev.kobj,
> > +				   "device");
> > +	if (result) {
> > +		dev_err(&pr->cdev->device,
> > +			"Failed to create sysfs link 'device'\n");
> > +		goto err_remove_sysfs_thermal;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_remove_sysfs_thermal:
> > +	sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
> > +err_thermal_unregister:
> > +	thermal_cooling_device_unregister(pr->cdev);
> > +
> > +	return result;
> > +}
> > +
> > +void acpi_processor_thermal_exit(struct acpi_processor *pr)
> > +{
> > +	struct acpi_device *device;
> > +
> > +	if (!pr)
> > +		return;
> > +
> > +	device = acpi_fetch_acpi_dev(pr->handle);
> > +	if (!device)
> > +		return;
>
> The same comment about passing the acpi_device structure applies here as
> well.
>
> > +
> > +	if (pr->cdev) {
> > +		sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
> > +		sysfs_remove_link(&pr->cdev->device.kobj, "device");
> > +		thermal_cooling_device_unregister(pr->cdev);
> > +		pr->cdev = NULL;
> > +	}
> > +}
>
> [...]