Re: [PATCH v1 10/15] platform/x86/amd/pmf: Add sysfs to toggle CnQF

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 7/27/22 22:52, Hans de Goede wrote:
> Hi,
> 
> On 7/12/22 16:58, Shyam Sundar S K wrote:
>> Whether to turn CnQF on/off by default upon driver load would be decided
>> by a BIOS flag. Add a sysfs node to provide a way to the user whether to
>> use static slider or CnQF .
>>
>> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> 
> Thanks, patch looks good to me:
> 
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Thinking more about this, there are userspace API questions here, see
my reply to patch 9/15.

Also ...

>> ---
>>  drivers/platform/x86/amd/pmf/cnqf.c | 52 +++++++++++++++++++++++++++++
>>  1 file changed, 52 insertions(+)
>>
>> diff --git a/drivers/platform/x86/amd/pmf/cnqf.c b/drivers/platform/x86/amd/pmf/cnqf.c
>> index 8c6756faab25..2b03ae1ad37f 100644
>> --- a/drivers/platform/x86/amd/pmf/cnqf.c
>> +++ b/drivers/platform/x86/amd/pmf/cnqf.c
>> @@ -302,9 +302,59 @@ void amd_pmf_load_defaults_cnqf(struct amd_pmf_dev *dev)
>>  		config_store.trans_prio[i] = i;
>>  }
>>  
>> +static ssize_t feat_store(struct device *dev,
>> +				  struct device_attribute *attr,
>> +				  const char *buf, size_t count)
>> +{
>> +	struct amd_pmf_dev *pdev = dev_get_drvdata(dev);
>> +	int result, src;
>> +	bool enabled;
>> +	u8 mode;
>> +
>> +	result = kstrtobool(buf, &enabled);
>> +	if (result)
>> +		return result;
>> +
>> +	src = amd_pmf_get_power_source();
>> +	pdev->cnqf_feat = enabled;
>> +	if (pdev->cnqf_feat) {
>> +		amd_pmf_handle_cnqf(pdev, SLIDER_OP_SET, src, config_store.current_mode, NULL);
>> +	} else {
>> +		pdev->cnqf_running = false;
>> +		mode = amd_pmf_get_pprof_modes(pdev);
>> +		amd_pmf_update_slider(pdev, SLIDER_OP_SET, mode, NULL);

This assumes that the static slider is always available on systems
with CnQF support, which is not checked anywhere.

Also work_buffer is still running here which will reset cnqf_running = true
after its first run, so this does not disable CnQF at all.

But maybe that is a bug in the amd_pmf_trans_cnqf() function ?

Maybe that function should not touch the cnqf_running flag; and it should
keep gathering statistics even when CqNF is disabled, but not actually
set the profile ?

Regards,

Hans



>> +	}
>> +
>> +	dev_dbg(pdev->dev, "Received CnQF %s\n", enabled ? "on" : "off");
>> +	return count;
>> +}
>> +
>> +static ssize_t feat_show(struct device *dev,
>> +				 struct device_attribute *attr,
>> +				 char *buf)
>> +{
>> +	struct amd_pmf_dev *pdev = dev_get_drvdata(dev);
>> +
>> +	return sprintf(buf, "%s\n", pdev->cnqf_feat ? "on" : "off");
>> +}
>> +
>> +static DEVICE_ATTR_RW(feat);
>> +
>> +static struct attribute *cnqf_feature_attrs[] = {
>> +	&dev_attr_feat.attr,
>> +	NULL
>> +};
>> +
>> +static const struct attribute_group cnqf_feature_attribute_group = {
>> +	.attrs = cnqf_feature_attrs,
>> +	.name = "cnqf"
>> +};
>> +
>>  void amd_pmf_deinit_cnqf(struct amd_pmf_dev *dev)
>>  {
>>  	cancel_delayed_work_sync(&dev->work_buffer);
>> +	sysfs_remove_group(&dev->dev->kobj, &cnqf_feature_attribute_group);
>> +	kobject_uevent(&dev->dev->kobj, KOBJ_CHANGE);
>>  }
>>  
>>  void amd_pmf_init_cnqf(struct amd_pmf_dev *dev)
>> @@ -324,4 +374,6 @@ void amd_pmf_init_cnqf(struct amd_pmf_dev *dev)
>>  	/* update the thermal for CnQF */
>>  	src = amd_pmf_get_power_source();
>>  	amd_pmf_handle_cnqf(dev, SLIDER_OP_SET, src, config_store.current_mode, NULL);
>> +	ret = sysfs_create_group(&dev->dev->kobj, &cnqf_feature_attribute_group);
>> +	kobject_uevent(&dev->dev->kobj, KOBJ_CHANGE);
>>  }