Re: [PATCH v3 2/2] hwmon: acpi_power_meter: convert to hwmon_device_register_with_info

[Guenter Roeck <linux@roeck-us.net>]

On 5/15/22 12:36, LABBE Corentin wrote:
> Le Wed, May 11, 2022 at 07:10:29PM -0700, Guenter Roeck a écrit :
>> Corentin,
>>
>> On 5/8/22 23:30, Corentin Labbe wrote:
>>> Booting lead to a hwmon_device_register() is deprecated. Please convert the driver to use hwmon_device_register_with_info().
>>> So let's convert the driver to use hwmon_device_register_with_info().
>>>
>>> Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
>>> ---
>> [ ... ]
>>
>>> @@ -836,20 +740,20 @@ static void acpi_power_meter_notify(struct acpi_device *device, u32 event)
>>>    		if (res)
>>>    			break;
>>>    
>>> -		remove_attrs(resource);
>>> +		remove_domain_devices(resource);
>>>    		setup_attrs(resource);
>>
>> Zhang Rui found an interesting problem with this code:
>> It needs a call to sysfs_update_groups(hwmon_dev->groups)
>> to update sysfs attribute visibility, probably between
>> remove_domain_devices() and setup_attrs().
>>
>>>    		break;
>>>    	case METER_NOTIFY_TRIP:
>>> -		sysfs_notify(&device->dev.kobj, NULL, POWER_AVERAGE_NAME);
>>> +		hwmon_notify_event(&device->dev, hwmon_power, hwmon_power_average, 0);
>>
>> ... which makes realize: The notification device should be the hwmon device.
>> That would be resource->hwmon_dev, not the acpi device.
>>
> 
> Hello
> 
> Since my hardware lacks capabilities testing this, I have emulated it on qemu:
> https://github.com/montjoie/qemu/commit/320f2ddacb954ab308ef699f66fca6313f75bc2b
> 
> I have added a custom ACPI _DBX method for triggering some ACPI state change. (like config change, like enabling CAP).
> 
> For testing config change I have tried lot of way:
>                  res = read_capabilities(resource);
> @@ -742,18 +758,22 @@ static void acpi_power_meter_notify(struct acpi_device *device, u32 event)
>   
>                  remove_domain_devices(resource);
>                  setup_attrs(resource);
> +               res = sysfs_update_groups(&resource->hwmon_dev->kobj, acpi_power_groups);
> +               res = sysfs_update_groups(&resource->acpi_dev->dev.kobj, acpi_power_groups);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_cap, 0);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_average, 0);

Did you add a debug log here ?

acpi_power_groups would be the wrong parameter for sysfs_update_groups().
It would have to be resource->hwmon_dev->groups.

Guenter

>                  break;
>          case METER_NOTIFY_TRIP:
> -               hwmon_notify_event(&device->dev, hwmon_power, hwmon_power_average, 0);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_average, 0);
>                  break;
>          case METER_NOTIFY_CAP:
> -               hwmon_notify_event(&device->dev, hwmon_power, hwmon_power_cap, 0);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_cap, 0);
>                  break;
>          case METER_NOTIFY_INTERVAL:
> -               hwmon_notify_event(&device->dev, hwmon_power, hwmon_power_average_interval, 0);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_average_interval, 0);
>                  break;
>          case METER_NOTIFY_CAPPING:
> -               hwmon_notify_event(&device->dev, hwmon_power, hwmon_power_alarm, 0);
> +               res = hwmon_notify_event(resource->hwmon_dev, hwmon_power, hwmon_power_alarm, 0);
>                  dev_info(&device->dev, "Capping in progress.\n");
>                  break;
>          default:
> 
> But nothing force visibility to be rerun.
> 
> Any idea on how to force visibility to be re-run ?