linux-kernel - Re: [PATCH 2/3] asus-wmi: Add dgpu disable method

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Message-ID: <knw744OJB1AYrrFpo77N1Eei0JZC3SjKzg6SMoMhOsEchAiE8-klOIPTyFCAUSiVeTopPNqgFSefQJ2av6Gs_cS4TuIRXVQcHUxvw8YvSl0=@protonmail.com>
Date:   Mon, 05 Jul 2021 00:47:31 +0000
From:   Barnabás Pőcze <pobrn@...tonmail.com>
To:     "Luke D. Jones" <luke@...nes.dev>
Cc:     hdegoede@...hat.com, corentin.chary@...il.com,
        mgross@...ux.intel.com, jdelvare@...e.com, linux@...ck-us.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] asus-wmi: Add dgpu disable method

Hi

I have added a couple comments inline.


2021. július 5., hétfő 0:21 keltezéssel, Luke D. Jones írta:

> In Windows the ASUS Armory Crate progrm can enable or disable the
                                        ^
"program"


> dGPU via a WMI call. This functions much the same as various Linux
> methods in software where the dGPU is removed from the device tree.
>
> However the WMI call saves the state of dGPU enabled or not and this

I think "[...] the WMI call saves whether the dGPU is enabled or not, and [...]"
might be better.
Or "[...] the WMI call saves the state of the dGPU (enabled or not) and [...]".


> then changes the dGPU visibility in Linux with no way for Linux
> users to re-enable it. We expose the WMI method so users can see
> and change the dGPU ACPI state.
>
> Signed-off-by: Luke D. Jones <luke@...nes.dev>
> ---
>  drivers/platform/x86/asus-wmi.c            | 98 ++++++++++++++++++++++
>  include/linux/platform_data/x86/asus-wmi.h |  3 +
>  2 files changed, 101 insertions(+)
>
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index 2468076d6cd8..8dc3f7ed021f 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -210,6 +210,9 @@ struct asus_wmi {
>  	u8 fan_boost_mode_mask;
>  	u8 fan_boost_mode;
>
> +	bool dgpu_disable_available;
> +	u8 dgpu_disable_mode;
> +
>  	bool throttle_thermal_policy_available;
>  	u8 throttle_thermal_policy_mode;
>
> @@ -427,6 +430,93 @@ static void lid_flip_tablet_mode_get_state(struct asus_wmi *asus)
>  	}
>  }
>
> +/* dGPU ********************************************************************/
> +static int dgpu_disable_check_present(struct asus_wmi *asus)
> +{
> +	u32 result;
> +	int err;
> +
> +	asus->dgpu_disable_available = false;
> +
> +	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_DGPU, &result);
> +	if (err) {
> +		if (err == -ENODEV)
> +			return 0;
> +		return err;
> +	}
> +
> +	if (result & ASUS_WMI_DSTS_PRESENCE_BIT)
> +		asus->dgpu_disable_available = true;
> +		asus->dgpu_disable_mode = result & ASUS_WMI_DSTS_STATUS_BIT;
> +

Aren't braces missing here?


> +	return 0;
> +}
> +
> +static int dgpu_disable_write(struct asus_wmi *asus)
> +{
> +	int err;
> +	u8 value;
> +	u32 retval;
> +
> +	value = asus->dgpu_disable_mode;
> +
> +	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_DGPU, value, &retval);
> +
> +	sysfs_notify(&asus->platform_device->dev.kobj, NULL,
> +			"dgpu_disable");

A similar line with the exact same length in patch 3/3 is not broken in two.
And shouldn't the notification be sent if the operation succeeded?


> +
> +	if (err) {
> +		pr_warn("Failed to set dgpu disable: %d\n", err);
> +		return err;
> +	}
> +
> +	if (retval > 1 || retval < 0) {
> +		pr_warn("Failed to set dgpu disable (retval): 0x%x\n",
> +			retval);
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static ssize_t dgpu_disable_show(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +	u8 mode = asus->dgpu_disable_mode;
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", mode);

You could use `sysfs_emit()`.


> +}
> +
> +static ssize_t dgpu_disable_store(struct device *dev,
> +				    struct device_attribute *attr,
> +				    const char *buf, size_t count)
> +{
> +	int result;
> +	u8 disable;
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +
> +	result = kstrtou8(buf, 10, &disable);

You could use `kstrtobool()`. I think that would be better since it accepts
'y', 'n', etc. in addition to 0 and 1.


> +	if (result < 0)
> +		return result;
> +
> +	if (disable > 1 || disable < 0)
> +		return -EINVAL;
> +
> +	asus->dgpu_disable_mode = disable;
> +	/*
> +	 * The ACPI call used does not save the mode unless the call is run twice.
> +	 * Once to disable, then once to check status and save - this is two code
> +	 * paths in the method in the ACPI dumps.
> +	*/
> +	dgpu_disable_write(asus);
> +	dgpu_disable_write(asus);

Is there any reason the potential error codes are not returned?


> +
> +	return count;
> +}
> +
> +static DEVICE_ATTR_RW(dgpu_disable);
> +
>  /* Battery ********************************************************************/
>
>  /* The battery maximum charging percentage */
> @@ -2412,6 +2502,7 @@ static struct attribute *platform_attributes[] = {
>  	&dev_attr_camera.attr,
>  	&dev_attr_cardr.attr,
>  	&dev_attr_touchpad.attr,
> +	&dev_attr_dgpu_disable.attr,
>  	&dev_attr_lid_resume.attr,
>  	&dev_attr_als_enable.attr,
>  	&dev_attr_fan_boost_mode.attr,
> @@ -2438,6 +2529,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
>  		devid = ASUS_WMI_DEVID_LID_RESUME;
>  	else if (attr == &dev_attr_als_enable.attr)
>  		devid = ASUS_WMI_DEVID_ALS_ENABLE;
> +	else if (attr == &dev_attr_dgpu_disable.attr)
> +		ok = asus->dgpu_disable_available;
>  	else if (attr == &dev_attr_fan_boost_mode.attr)
>  		ok = asus->fan_boost_mode_available;
>  	else if (attr == &dev_attr_throttle_thermal_policy.attr)
> @@ -2699,6 +2792,10 @@ static int asus_wmi_add(struct platform_device *pdev)
>  	if (err)
>  		goto fail_platform;
>
> +	err = dgpu_disable_check_present(asus);
> +	if (err)
> +		goto fail_dgpu_disable;
> +

Should this really be considered a "fatal" error?


>  	err = fan_boost_mode_check_present(asus);
>  	if (err)
>  		goto fail_fan_boost_mode;
> @@ -2799,6 +2896,7 @@ static int asus_wmi_add(struct platform_device *pdev)
>  fail_sysfs:
>  fail_throttle_thermal_policy:
>  fail_fan_boost_mode:
> +fail_dgpu_disable:
>  fail_platform:
>  fail_panel_od:
>  	kfree(asus);
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 428aea701c7b..a528f9d0e4b7 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -90,6 +90,9 @@
>  /* Keyboard dock */
>  #define ASUS_WMI_DEVID_KBD_DOCK		0x00120063
>
> +/* dgpu on/off */
> +#define ASUS_WMI_DEVID_DGPU		0x00090020
> +
>  /* DSTS masks */
>  #define ASUS_WMI_DSTS_STATUS_BIT	0x00000001
>  #define ASUS_WMI_DSTS_UNKNOWN_BIT	0x00000002
> --
> 2.31.1


Regards,
Barnabás Pőcze