Re: [PATCH 1/2] platform/x86: wmi: Fix WMI event enablement

[Armin Wolf <W_Armin@gmx.de>]

Am 25.06.25 um 14:28 schrieb Ilpo Järvinen:

> On Fri, 20 Jun 2025, Armin Wolf wrote:
>
>> It turns out that the Windows WMI-ACPI driver always enables/disables
>> WMI events regardless of whether they are marked as expensive or not.
>> This finding is further reinforced when reading the documentation of
>> the WMI_FUNCTION_CONTROL_CALLBACK callback used by Windows drivers
>> for enabling/disabling WMI devices:
>>
>> 	The DpWmiFunctionControl routine enables or disables
>> 	notification of events, and enables or disables data
>> 	collection for data blocks that the driver registered
>> 	as expensive to collect.
>>
>> Follow this behavior to fix the WMI event used for reporting hotkey
>> events on the Dell Latitude 5400 and likely many more devices.
>>
>> Reported-by: Dmytro Bagrii <dimich.dmb@gmail.com>
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220246
>> Tested-by: Dmytro Bagrii <dimich.dmb@gmail.com>
>> Fixes: 656f0961d126 ("platform/x86: wmi: Rework WCxx/WExx ACPI method handling")
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>>   drivers/platform/x86/wmi.c | 16 +++++++++++-----
>>   1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
>> index 21b7e54bd7ab..4e86a422f05f 100644
>> --- a/drivers/platform/x86/wmi.c
>> +++ b/drivers/platform/x86/wmi.c
>> @@ -180,16 +180,22 @@ static int wmi_device_enable(struct wmi_device *wdev, bool enable)
>>   	acpi_handle handle;
>>   	acpi_status status;
>>   
>> -	if (!(wblock->gblock.flags & ACPI_WMI_EXPENSIVE))
>> -		return 0;
>> -
>>   	if (wblock->dev.dev.type == &wmi_type_method)
>>   		return 0;
>>   
>> -	if (wblock->dev.dev.type == &wmi_type_event)
>> +	if (wblock->dev.dev.type == &wmi_type_event) {
>> +		/*
>> +		 * Windows always enables/disables WMI events, even when they are
>> +		 * not marked as being expensive. We follow this behavior for
> Hi Armin,
>
> Is the wording in the comment reversed? (I suspect you didn't mean to
> include "not" into that statement?)

Actually i did.

The WMI-ACPI spec seemed to suggest that WMI events should be enabled/disabled
only if they are being marked as expensive, however it turned out that WMI events
should also be enabled/disabled even if _not_ marked as being expensive.

Besides that another user tested this patch on his machine, so:

Tested-by: Grzegorz Suwaj <grzegorzssuwaj@gmail.com>

Thanks,
Armin Wolf

>> +		 * compatibility reasons.
>> +		 */
>>   		snprintf(method, sizeof(method), "WE%02X", wblock->gblock.notify_id);
>> -	else
>> +	} else {
>> +		if (!(wblock->gblock.flags & ACPI_WMI_EXPENSIVE))
>> +			return 0;
>> +
>>   		get_acpi_method_name(wblock, 'C', method);
>> +	}
>>   
>>   	/*
>>   	 * Not all WMI devices marked as expensive actually implement the
>>