Re: [PATCH v2 8/9] platform/x86: asus-wmi: Add support for MCU powersave

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 2 Apr 2024, Luke D. Jones wrote:

> Add support for an MCU powersave WMI call. This is intended to set the
> MCU in to a low-power mode when sleeping. This mode can cut sleep power
> use by around half.
> 
> Signed-off-by: Luke D. Jones <luke@ljones.dev>

Hi,

I fail to follow the logic of the patch here. This patch makes it 
configurable which is not bad in itself but what is the reason why a user 
would not always want to cut sleep power usage down? So this sounds like a 
feature that the user wants always enabled if available.

So what are the downsides of enabling it if it's supported?

-- 
 i.


> ---
>  .../ABI/testing/sysfs-platform-asus-wmi       | 11 +++-
>  drivers/platform/x86/asus-wmi.c               | 50 +++++++++++++++++++
>  2 files changed, 60 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> index 41b92e53e88a..28144371a0f1 100644
> --- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
> +++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> @@ -202,4 +202,13 @@ Contact:	"Luke Jones" <luke@ljones.dev>
>  Description:
>  		Set if the BIOS POST sound is played on boot.
>  			* 0 - False,
> -			* 1 - True
> \ No newline at end of file
> +			* 1 - True
> +
> +What:		/sys/devices/platform/<platform>/mcu_powersave
> +Date:		Apr 2024
> +KernelVersion:	6.10
> +Contact:	"Luke Jones" <luke@ljones.dev>
> +Description:
> +		Set if the MCU can go in to low-power mode on system sleep
> +			* 0 - False,
> +			* 1 - True
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index ddf568ef8c5e..cf872eed0986 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -1292,6 +1292,53 @@ static ssize_t nv_temp_target_show(struct device *dev,
>  }
>  static DEVICE_ATTR_RW(nv_temp_target);
>  
> +/* Ally MCU Powersave ********************************************************/
> +static ssize_t mcu_powersave_show(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +	int result;
> +
> +	result = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_MCU_POWERSAVE);
> +	if (result < 0)
> +		return result;
> +
> +	return sysfs_emit(buf, "%d\n", result);
> +}
> +
> +static ssize_t mcu_powersave_store(struct device *dev,
> +				    struct device_attribute *attr,
> +				    const char *buf, size_t count)
> +{
> +	int result, err;
> +	u32 enable;
> +
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +
> +	result = kstrtou32(buf, 10, &enable);
> +	if (result)
> +		return result;
> +
> +	if (enable > 1)
> +		return -EINVAL;
> +
> +	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_MCU_POWERSAVE, enable, &result);
> +	if (err) {
> +		pr_warn("Failed to set MCU powersave: %d\n", err);
> +		return err;
> +	}
> +
> +	if (result > 1) {
> +		pr_warn("Failed to set MCU powersave (result): 0x%x\n", result);
> +		return -EIO;
> +	}
> +
> +	sysfs_notify(&asus->platform_device->dev.kobj, NULL, "mcu_powersave");
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(mcu_powersave);
> +
>  /* Battery ********************************************************************/
>  
>  /* The battery maximum charging percentage */
> @@ -4299,6 +4346,7 @@ static struct attribute *platform_attributes[] = {
>  	&dev_attr_ppt_platform_sppt.attr,
>  	&dev_attr_nv_dynamic_boost.attr,
>  	&dev_attr_nv_temp_target.attr,
> +	&dev_attr_mcu_powersave.attr,
>  	&dev_attr_boot_sound.attr,
>  	&dev_attr_panel_od.attr,
>  	&dev_attr_mini_led_mode.attr,
> @@ -4352,6 +4400,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
>  		devid = ASUS_WMI_DEVID_NV_DYN_BOOST;
>  	else if (attr == &dev_attr_nv_temp_target.attr)
>  		devid = ASUS_WMI_DEVID_NV_THERM_TARGET;
> +	else if (attr == &dev_attr_mcu_powersave.attr)
> +		devid = ASUS_WMI_DEVID_MCU_POWERSAVE;
>  	else if (attr == &dev_attr_boot_sound.attr)
>  		devid = ASUS_WMI_DEVID_BOOT_SOUND;
>  	else if (attr == &dev_attr_panel_od.attr)
>