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Date:   Mon, 15 Aug 2022 23:16:12 -0500
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Subject: Re: [PATCH] asus-wmi: Support the hardware GPU MUX on some laptops
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To:     "Luke D. Jones" <luke@ljones.dev>, hdegoede@redhat.com
Cc:     markgross@kernel.org, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20220813092624.6228-1-luke@ljones.dev>
From:   Mario Limonciello <mario.limonciello@amd.com>
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On 8/13/22 04:26, Luke D. Jones wrote:
> Support the hardware GPU MUX switch available on some models. This
> switch can toggle the MUX between:
> 
> - 0, Dedicated mode
> - 1, Optimus mode
> 
> Optimus mode is the regular iGPU + dGPU available, while dedicated
> mode switches the system to have only the dGPU available.
> 
> Signed-off-by: Luke D. Jones <luke@ljones.dev>
> ---
>   .../ABI/testing/sysfs-platform-asus-wmi       | 11 ++++
>   drivers/platform/x86/asus-wmi.c               | 62 +++++++++++++++++++
>   include/linux/platform_data/x86/asus-wmi.h    |  3 +
>   3 files changed, 76 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> index 574b5170a37d..03124eab7f01 100644
> --- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
> +++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> @@ -58,6 +58,17 @@ Description:
>   			* 1 - overboost,
>   			* 2 - silent
>   
> +What:          /sys/devices/platform/<platform>/gpu_mux_mode
> +Date:          Aug 2022
> +KernelVersion: 6.1
> +Contact:       "Luke Jones" <luke@ljones.dev>
> +Description:
> +               Switch the GPU hardware MUX mode. Laptops with this feature can
> +			   can be toggled to boot with only the dGPU (discrete mode) or in
> +			   standard Optimus/Hybrid mode. On switch a reboot is required:
> +                       * 0 - Discrete GPU,
> +                       * 1 - Optimus/Hybrid,

This feel like it should probably export using 
/sys/class/firmware-attributes.  That's exactly how those types of 
attributes work.

As a bonus, software like fwupd 1.8.4 knows how to manipulate it and you 
don't need special documentation.

> +
>   What:          /sys/devices/platform/<platform>/dgpu_disable
>   Date:          Aug 2022
>   KernelVersion: 5.17
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index e2b51b5550e8..0421ffb81927 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -230,6 +230,7 @@ struct asus_wmi {
>   
>   	bool egpu_enable_available;
>   	bool dgpu_disable_available;
> +	bool gpu_mux_mode_available;
>   
>   	bool throttle_thermal_policy_available;
>   	u8 throttle_thermal_policy_mode;
> @@ -668,6 +669,59 @@ static ssize_t egpu_enable_store(struct device *dev,
>   }
>   static DEVICE_ATTR_RW(egpu_enable);
>   
> +/* gpu mux switch *************************************************************/
> +static int gpu_mux_mode_check_present(struct asus_wmi *asus)
> +{
> +	asus->gpu_mux_mode_available = asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_GPU_MUX);
> +
> +   return 0;
> +}
> +
> +static ssize_t gpu_mux_mode_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_GPU_MUX);
> +   if (result < 0)
> +       return result;
> +
> +   return sysfs_emit(buf, "%d\n", result);
> +}
> +
> +static ssize_t gpu_mux_mode_store(struct device *dev,
> +                   struct device_attribute *attr,
> +                   const char *buf, size_t count)
> +{
> +   struct asus_wmi *asus = dev_get_drvdata(dev);
> +   int result, err;
> +   u32 optimus;
> +
> +   err = kstrtou32(buf, 10, &optimus);
> +   if (err)
> +       return err;
> +
> +   if (optimus > 1)
> +       return -EINVAL;
> +
> +   err = asus_wmi_set_devstate(ASUS_WMI_DEVID_GPU_MUX, optimus, &result);
> +   if (err) {
> +       dev_err(dev, "Failed to set GPU MUX mode: %d\n", err);
> +       return err;
> +   }
> +	/* !1 is considered a fail by ASUS */
> +	if (result != 1) {
> +		dev_warn(dev, "Failed to set GPU MUX mode (result): 0x%x\n", result);
> +       return -EIO;
> +   }
> +
> +   sysfs_notify(&asus->platform_device->dev.kobj, NULL, "gpu_mux_mode");
> +
> +   return count;
> +}
> +static DEVICE_ATTR_RW(gpu_mux_mode);
> +
>   /* Battery ********************************************************************/
>   
>   /* The battery maximum charging percentage */
> @@ -3165,6 +3219,7 @@ static struct attribute *platform_attributes[] = {
>   	&dev_attr_touchpad.attr,
>   	&dev_attr_egpu_enable.attr,
>   	&dev_attr_dgpu_disable.attr,
> +	&dev_attr_gpu_mux_mode.attr,
>   	&dev_attr_lid_resume.attr,
>   	&dev_attr_als_enable.attr,
>   	&dev_attr_fan_boost_mode.attr,
> @@ -3195,6 +3250,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
>   		ok = asus->egpu_enable_available;
>   	else if (attr == &dev_attr_dgpu_disable.attr)
>   		ok = asus->dgpu_disable_available;
> +	else if (attr == &dev_attr_gpu_mux_mode.attr)
> +		ok = asus->gpu_mux_mode_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)
> @@ -3464,6 +3521,10 @@ static int asus_wmi_add(struct platform_device *pdev)
>   	if (err)
>   		goto fail_dgpu_disable;
>   
> +	err = gpu_mux_mode_check_present(asus);
> +   if (err)
> +       goto fail_gpu_mux_mode;
> +
>   	err = fan_boost_mode_check_present(asus);
>   	if (err)
>   		goto fail_fan_boost_mode;
> @@ -3578,6 +3639,7 @@ static int asus_wmi_add(struct platform_device *pdev)
>   fail_fan_boost_mode:
>   fail_egpu_enable:
>   fail_dgpu_disable:
> +fail_gpu_mux_mode:
>   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 a571b47ff362..c023332842a2 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -98,6 +98,9 @@
>   /* dgpu on/off */
>   #define ASUS_WMI_DEVID_DGPU		0x00090020
>   
> +/* gpu mux switch, 0 = dGPU, 1 = Optimus */
> +#define ASUS_WMI_DEVID_GPU_MUX 0x00090016
> +
>   /* DSTS masks */
>   #define ASUS_WMI_DSTS_STATUS_BIT	0x00000001
>   #define ASUS_WMI_DSTS_UNKNOWN_BIT	0x00000002