Re: [PATCH v3 2/6] platform/x86: lenovo-wmi-other: Limit adding attributes to supported devices

[Derek J. Clark]

On February 24, 2026 12:47:56 AM PST, "Ilpo Järvinen" <ilpo.jarvinen@xxxxxxxxxxxxxxx> wrote:
>On Tue, 24 Feb 2026, Derek J. Clark wrote:
>
>> Adds lwmi_is_attr_01_supported, and only creates the attribute subfolder
>> if the attribute is supported by the hardware. Due to some poorly
>> implemented BIOS, this is a multi-step sequence of events. This is
>> because:
>> - Some BIOS support getting the capability data from custom mode (0xff),
>>   while others only support it in no-mode (0x00).
>> - Similarly, some BIOS support get/set for the current value from custom
>>   mode (0xff), while others only support it in no-mode (0x00).
>> - Some BIOS report capability data for a method that is not fully
>>   implemented.
>> - Some BIOS have methods fully implemented, but no complimentary
>>   capability data.
>> 
>> To ensure we only expose fully implemented methods with corresponding
>> capability data, we check each outcome before reporting that an
>> attribute can be supported.
>> 
>> Checking for lwmi_is_attr_01_supported during remove is not done to
>> ensure that we don't attempt to call cd01 or send WMI events if one of
>> the interfaces being removed was the cause of the driver unloading.
>> 
>
>> While adding members to tunable_attr_01, remove unused capdata pointer
>> and limit size of all ID's to the appropriate size.
>
>Please don't mix changes like this. Create a seprate patch for it.
>
>> Reviewed-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
>> Reported-by: Kurt Borja <kuurtb@xxxxxxxxx>
>> Closes: https://lore.kernel.org/platform-driver-x86/DG60P3SHXR8H.3NSEHMZ6J7XRC@xxxxxxxxx/
>> Signed-off-by: Derek J. Clark <derekjohn.clark@xxxxxxxxx>
>> ---
>>  drivers/platform/x86/lenovo/wmi-other.c | 117 +++++++++++++++++++++---
>>  1 file changed, 102 insertions(+), 15 deletions(-)
>> 
>> diff --git a/drivers/platform/x86/lenovo/wmi-other.c b/drivers/platform/x86/lenovo/wmi-other.c
>> index 95886df39c8d..f3f12303e379 100644
>> --- a/drivers/platform/x86/lenovo/wmi-other.c
>> +++ b/drivers/platform/x86/lenovo/wmi-other.c
>> @@ -545,11 +545,12 @@ static void lwmi_om_fan_info_collect_cd_fan(struct device *dev, struct cd_list *
>>  /* ======== fw_attributes (component: lenovo-wmi-capdata 01) ======== */
>>  
>>  struct tunable_attr_01 {
>> -	struct capdata01 *capdata;
>>  	struct device *dev;
>> -	u32 feature_id;
>> -	u32 device_id;
>> -	u32 type_id;
>> +	u8 feature_id;
>> +	u8 device_id;
>> +	u8 type_id;
>> +	u8 cd_mode_id; /* mode arg for searching capdata */
>> +	u8 cv_mode_id; /* mode arg for set/get current_value */
>>  };
>>  
>>  static struct tunable_attr_01 ppt_pl1_spl = {
>> @@ -716,7 +717,7 @@ static ssize_t attr_capdata01_show(struct kobject *kobj,
>>  	int value, ret;
>>  
>>  	attribute_id = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>> -				    LWMI_GZ_THERMAL_MODE_CUSTOM, tunable_attr->type_id);
>> +				    tunable_attr->cd_mode_id, tunable_attr->type_id);
>>  
>>  	ret = lwmi_cd01_get_data(priv->cd01_list, attribute_id, &capdata);
>>  	if (ret)
>> @@ -782,7 +783,7 @@ static ssize_t attr_current_value_store(struct kobject *kobj,
>>  		return -EBUSY;
>>  
>>  	args.arg0 = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>> -				 mode, tunable_attr->type_id);
>> +				 tunable_attr->cd_mode_id, tunable_attr->type_id);
>>  
>>  	ret = lwmi_cd01_get_data(priv->cd01_list, args.arg0, &capdata);
>>  	if (ret)
>> @@ -795,6 +796,8 @@ static ssize_t attr_current_value_store(struct kobject *kobj,
>>  	if (value < capdata.min_value || value > capdata.max_value)
>>  		return -EINVAL;
>>  
>> +	args.arg0 = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>> +				 tunable_attr->cv_mode_id, tunable_attr->type_id);
>>  	args.arg1 = value;
>>  
>>  	ret = lwmi_dev_evaluate_int(priv->wdev, 0x0, LWMI_FEATURE_VALUE_SET,
>> @@ -828,13 +831,16 @@ static ssize_t attr_current_value_show(struct kobject *kobj,
>>  	struct lwmi_om_priv *priv = dev_get_drvdata(tunable_attr->dev);
>>  	struct wmi_method_args_32 args;
>>  	enum thermal_mode mode;
>> -	int retval;
>> -	int ret;
>> +	int retval, ret;
>>  
>>  	ret = lwmi_om_notifier_call(&mode);
>>  	if (ret)
>>  		return ret;
>>  
>> +	/* If "no-mode" is the supported mode, ensure we never send current mode */
>> +	if (tunable_attr->cv_mode_id == LWMI_GZ_THERMAL_MODE_NONE)
>> +		mode = tunable_attr->cv_mode_id;
>> +
>>  	args.arg0 = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>>  				 mode, tunable_attr->type_id);
>>  
>> @@ -847,6 +853,85 @@ static ssize_t attr_current_value_show(struct kobject *kobj,
>>  	return sysfs_emit(buf, "%d\n", retval);
>>  }
>>  
>> +/**
>> + * lwmi_attr_01_is_supported() - Determine if the given attribute is supported.
>> + * @tunable_attr: The attribute to verify.
>> + *
>> + * First check if the attribute has a corresponding capdata01 table in the cd01
>> + * module under the "custom" mode (0xff). If that is not present then check if
>> + * there is a corresponding "no-mode" (0x00) entry. If either of those passes,
>> + * check capdata->supported for values > 0. If capdata is available, attempt to
>> + * determine the set/get mode for the current value property using a similar
>> + * pattern. If the value returned by either custom or no-mode is 0, or we get
>> + * an error, we assume that mode is not supported. If any of the above checks
>> + * fail then the attribute is not fully supported.
>> + *
>> + * The probed cd_mode_id/cv_mode_id are stored on the tunable_attr for later
>> + * reference.
>> + *
>> + * Return: Support level, or an error code.
>> + */
>> +static int lwmi_attr_01_is_supported(struct tunable_attr_01 *tunable_attr)
>> +{
>> +	struct lwmi_om_priv *priv = dev_get_drvdata(tunable_attr->dev);
>> +	u8 mode = LWMI_GZ_THERMAL_MODE_CUSTOM;
>> +	struct wmi_method_args_32 args;
>> +	struct capdata01 capdata;
>> +	int retval, ret;
>> +
>> +	/* Determine tunable_attr->cd_mode_id */
>> +no_mode_fallback_1:
>> +	args.arg0 = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>> +				 mode, tunable_attr->type_id);
>> +
>> +	ret = lwmi_cd01_get_data(priv->cd01_list, args.arg0, &capdata);
>> +	if (ret && mode) {
>> +		dev_dbg(tunable_attr->dev, "Attribute id %x not supported\n", args.arg0);
>
>Add include.
>
>> +		mode = LWMI_GZ_THERMAL_MODE_NONE;
>> +		goto no_mode_fallback_1;
>
>Is it possible to make a helper so you don't need these back gotos?
>

Sure. How about I put both modes into an array and loop through them, passing the values to a function that will evaluate it. I can break if there is a match and throw an error if there's no match at the end.

>> +	}
>> +	if (ret)
>> +		goto not_supported;
>> +	if (!capdata.supported) {
>> +		ret = -EOPNOTSUPP;
>> +		goto not_supported;
>> +	}
>> +
>> +	tunable_attr->cd_mode_id = mode;
>> +
>> +	/* Determine tunable_attr->cv_mode_id */
>> +	mode = LWMI_GZ_THERMAL_MODE_CUSTOM;
>> +no_mode_fallback_2:
>> +	args.arg0 = LWMI_ATTR_ID(tunable_attr->device_id, tunable_attr->feature_id,
>> +				 mode, tunable_attr->type_id);
>> +
>> +	ret = lwmi_dev_evaluate_int(priv->wdev, 0x0, LWMI_FEATURE_VALUE_GET,
>> +				    (unsigned char *)&args, sizeof(args),
>> +				    &retval);
>> +	if ((ret && mode) || (!retval && mode)) {
>> +		dev_dbg(tunable_attr->dev, "Attribute id %x not supported\n", args.arg0);
>> +		mode = LWMI_GZ_THERMAL_MODE_NONE;
>> +		goto no_mode_fallback_2;
>
>Same question here?
>
>> +	}
>> +	if (ret)
>> +		goto not_supported;
>> +	if (retval == 0) {
>> +		ret = -EOPNOTSUPP;
>> +		goto not_supported;
>> +	}
>> +
>> +	tunable_attr->cv_mode_id = mode;
>> +	dev_dbg(tunable_attr->dev, "cd_mode_id: %02x%02x%02x%02x, cv_mode_id: %#08x attribute support level: %x\n",
>> +		tunable_attr->device_id, tunable_attr->feature_id, tunable_attr->cd_mode_id,
>> +		tunable_attr->type_id, args.arg0, capdata.supported);
>> +
>> +	return capdata.supported;
>> +
>> +not_supported:
>> +	dev_dbg(tunable_attr->dev, "Attribute id %x not supported\n", args.arg0);
>> +	return ret;
>> +}
>> +
>>  /* Lenovo WMI Other Mode Attribute macros */
>>  #define __LWMI_ATTR_RO(_func, _name)                                  \
>>  	{                                                             \
>> @@ -970,19 +1055,21 @@ static int lwmi_om_fw_attr_add(struct lwmi_om_priv *priv)
>>  	}
>>  
>>  	for (i = 0; i < ARRAY_SIZE(cd01_attr_groups) - 1; i++) {
>> -		err = sysfs_create_group(&priv->fw_attr_kset->kobj,
>> -					 cd01_attr_groups[i].attr_group);
>> -		if (err)
>> -			goto err_remove_groups;
>> -
>>  		cd01_attr_groups[i].tunable_attr->dev = &priv->wdev->dev;
>> +		if (lwmi_attr_01_is_supported(cd01_attr_groups[i].tunable_attr) > 0) {
>
>Reverse logic and use continue.
>
>> +			err = sysfs_create_group(&priv->fw_attr_kset->kobj,
>> +						 cd01_attr_groups[i].attr_group);
>> +			if (err)
>> +				goto err_remove_groups;
>> +		}
>>  	}
>>  	return 0;
>>  
>>  err_remove_groups:
>>  	while (i--)
>> -		sysfs_remove_group(&priv->fw_attr_kset->kobj,
>> -				   cd01_attr_groups[i].attr_group);
>> +		if (lwmi_attr_01_is_supported(cd01_attr_groups[i].tunable_attr) > 0)
>
>Reverse logic + continue.
>
>> +			sysfs_remove_group(&priv->fw_attr_kset->kobj,
>> +					   cd01_attr_groups[i].attr_group);
>
>You need to add braces for multiline constructs.
>
>>  
>>  	kset_unregister(priv->fw_attr_kset);
>>  
>> 
>