Re: [PATCH v3 2/3] drm/amdgpu: add Apple GMUX runtime PM support

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

On Wed, 12 Aug 2026, Andre Eikmeyer wrote:

> The MacBookPro15,1 uses Apple GMUX to control power to the discrete GPU,
> but it does not expose the ATPX or ACPI power-resource interfaces currently
> recognized by amdgpu. The driver therefore leaves runtime PM disabled even
> though vga_switcheroo can switch the GPU reliably.
> 
> A dedicated GMUX runtime PM mode uses the existing vga_switcheroo PM domain
> to sequence GPU power. A runtime-suspended GMUX GPU can remain powered off
> across system sleep, following the smart-suspend handling already used by
> BOCO devices.
> 
> This allows the discrete GPU to enter D3cold while the integrated GPU is
> primary and allows PRIME workloads and external displays to wake it on
> demand. The model enablement is limited to the tested MacBookPro15,1.
> 
> This was tested on both the 2018 and 2019 MacBookPro15,1 revisions together
> with the apple-gmux and HDA changes in this series.
> 
> Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  1 +
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 34 ++++++++++++++++++----
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 30 ++++++++++++-------
>  drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h    |  1 +
>  4 files changed, 49 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 7b09410..cc2e2e2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1402,6 +1402,7 @@ int amdgpu_device_mode1_reset(struct amdgpu_device *adev);
>  int amdgpu_device_link_reset(struct amdgpu_device *adev);
>  bool amdgpu_device_supports_atpx(struct amdgpu_device *adev);
>  bool amdgpu_device_supports_px(struct amdgpu_device *adev);
> +bool amdgpu_device_supports_gmux(struct amdgpu_device *adev);
>  bool amdgpu_device_supports_boco(struct amdgpu_device *adev);
>  bool amdgpu_device_supports_smart_shift(struct amdgpu_device *adev);
>  int amdgpu_device_supports_baco(struct amdgpu_device *adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index bff3e06..bfa2b7a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -34,6 +34,7 @@
>  #include <linux/slab.h>
>  #include <linux/iommu.h>
>  #include <linux/pci.h>
> +#include <linux/dmi.h>
>  #include <linux/pci-p2pdma.h>
>  #include <linux/apple-gmux.h>
>  #include <linux/nospec.h>
> @@ -568,6 +569,22 @@ bool amdgpu_device_supports_px(struct amdgpu_device *adev)
>  	return false;
>  }
>  
> +static const struct dmi_system_id amdgpu_gmux_runpm_dmi_table[] = {
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro15,1"),
> +		},
> +	},
> +	{ }
> +};
> +
> +bool amdgpu_device_supports_gmux(struct amdgpu_device *adev)
> +{
> +	return dmi_check_system(amdgpu_gmux_runpm_dmi_table) &&
> +	       !dev_is_removable(&adev->pdev->dev) &&
> +	       apple_gmux_detect(NULL, NULL);
> +}
> +
>  /**
>   * amdgpu_device_supports_boco - Is the device a dGPU with ACPI power resources
>   *
> @@ -631,6 +648,9 @@ void amdgpu_device_detect_runtime_pm_mode(struct amdgpu_device *adev)
>  			/* enable PX as runtime mode */
>  			adev->pm.rpm_mode = AMDGPU_RUNPM_PX;
>  			dev_info(adev->dev, "Using ATPX for runtime pm\n");
> +		} else if (amdgpu_device_supports_gmux(adev)) {
> +			adev->pm.rpm_mode = AMDGPU_RUNPM_GMUX;
> +			dev_info(adev->dev, "Using Apple GMUX for runtime pm\n");
>  		} else if (amdgpu_device_supports_boco(adev)) {
>  			/* enable boco as runtime mode */
>  			adev->pm.rpm_mode = AMDGPU_RUNPM_BOCO;
> @@ -3711,7 +3731,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>  {
>  	struct pci_dev *pdev = adev->pdev;
>  	int r, i;
> -	bool px = false;
> +	bool gmux, px = false;
>  	u32 max_MBps;
>  	int tmp;
>  
> @@ -4144,13 +4164,14 @@ fence_driver_init:
>  		vga_client_register(adev->pdev, amdgpu_device_vga_set_decode);
>  
>  	px = amdgpu_device_supports_px(adev);
> +	gmux = amdgpu_device_supports_gmux(adev);
>  
>  	if (px || (!dev_is_removable(&adev->pdev->dev) &&
> -				apple_gmux_detect(NULL, NULL)))
> +		   apple_gmux_detect(NULL, NULL)))

Please don't make unrelated space changes in a logic change.

>  		vga_switcheroo_register_client(adev->pdev,
> -					       &amdgpu_switcheroo_ops, px);
> +					       &amdgpu_switcheroo_ops, px || gmux);
>  
> -	if (px)
> +	if (px || gmux)
>  		vga_switcheroo_init_domain_pm_ops(adev->dev, &adev->vga_pm_domain);
>  
>  	adev->pm_nb.notifier_call = amdgpu_device_pm_notifier;
> @@ -4278,7 +4299,7 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
>  void amdgpu_device_fini_sw(struct amdgpu_device *adev)
>  {
>  	int i, idx;
> -	bool px;
> +	bool gmux, px;
>  
>  	amdgpu_device_ip_fini(adev);
>  	amdgpu_fence_driver_sw_fini(adev);
> @@ -4309,12 +4330,13 @@ void amdgpu_device_fini_sw(struct amdgpu_device *adev)
>  	adev->xcp_mgr = NULL;
>  
>  	px = amdgpu_device_supports_px(adev);
> +	gmux = amdgpu_device_supports_gmux(adev);
>  
>  	if (px || (!dev_is_removable(&adev->pdev->dev) &&
>  				apple_gmux_detect(NULL, NULL)))
>  		vga_switcheroo_unregister_client(adev->pdev);
>  
> -	if (px)
> +	if (px || gmux)
>  		vga_switcheroo_fini_domain_pm_ops(adev->dev);
>  
>  	if ((adev->pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 1aed121..b8d4273 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -2485,11 +2485,12 @@ retry_init:
>  		DRM_ERROR("Creating debugfs files failed (%d).\n", ret);
>  
>  	if (adev->pm.rpm_mode != AMDGPU_RUNPM_NONE) {
> -		/* only need to skip on ATPX */
> +		/* ATPX requires a full system-sleep transition. */
>  		if (amdgpu_device_supports_px(adev))
>  			dev_pm_set_driver_flags(ddev->dev, DPM_FLAG_NO_DIRECT_COMPLETE);
> -		/* we want direct complete for BOCO */
> -		if (amdgpu_device_supports_boco(adev))
> +		/* BOCO and GMUX can remain runtime suspended across system sleep. */
> +		if (amdgpu_device_supports_boco(adev) ||
> +		    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX)
>  			dev_pm_set_driver_flags(ddev->dev, DPM_FLAG_SMART_PREPARE |
>  						DPM_FLAG_SMART_SUSPEND |
>  						DPM_FLAG_MAY_SKIP_RESUME);
> @@ -2598,7 +2599,9 @@ static int amdgpu_pmops_prepare(struct device *dev)
>  	/* Return a positive number here so
>  	 * DPM_FLAG_SMART_SUSPEND works properly
>  	 */
> -	if (amdgpu_device_supports_boco(adev) && pm_runtime_suspended(dev))
> +	if ((amdgpu_device_supports_boco(adev) ||
> +	     adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX) &&
> +	    pm_runtime_suspended(dev))
>  		return 1;
>  
>  	/* if we will not support s3 or s2i for the device
> @@ -2860,7 +2863,8 @@ static int amdgpu_pmops_runtime_suspend(struct device *dev)
>  	}
>  
>  	adev->in_runpm = true;
> -	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX)
> +	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX ||
> +	    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX)
>  		drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
>  
>  	/*
> @@ -2887,8 +2891,9 @@ static int amdgpu_pmops_runtime_suspend(struct device *dev)
>  	if (adev->pm.rpm_mode == AMDGPU_RUNPM_BOCO)
>  		adev->mp1_state = PP_MP1_STATE_NONE;
>  
> -	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX) {
> -		/* Only need to handle PCI state in the driver for ATPX
> +	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX ||
> +	    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX) {
> +		/* Only need to handle PCI state in the driver for ATPX and GMUX.
>  		 * PCI core handles it for _PR3.
>  		 */
>  		amdgpu_device_cache_pci_state(pdev);
> @@ -2935,10 +2940,11 @@ static int amdgpu_pmops_runtime_resume(struct device *dev)
>  	if (!pci_device_is_present(adev->pdev))
>  		adev->no_hw_access = true;
>  
> -	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX) {
> +	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX ||
> +	    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX) {
>  		drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
>  
> -		/* Only need to handle PCI state in the driver for ATPX
> +		/* Only need to handle PCI state in the driver for ATPX and GMUX.
>  		 * PCI core handles it for _PR3.
>  		 */
>  		pci_set_power_state(pdev, PCI_D0);
> @@ -2958,12 +2964,14 @@ static int amdgpu_pmops_runtime_resume(struct device *dev)
>  	}
>  	ret = amdgpu_device_resume(drm_dev, false);
>  	if (ret) {
> -		if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX)
> +		if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX ||
> +		    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX)
>  			pci_disable_device(pdev);
>  		return ret;
>  	}
>  
> -	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX)
> +	if (adev->pm.rpm_mode == AMDGPU_RUNPM_PX ||
> +	    adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX)

Maybe helper to check these? (But I'm not the maintainer for this code so 
I don't know what they want.)

>  		drm_dev->switch_power_state = DRM_SWITCH_POWER_ON;
>  
>  	amdgpu_restore_umd_profile_pstate_after_runpm(adev);
> diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> index 8d1b097..df24b01 100644
> --- a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> +++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> @@ -48,6 +48,7 @@ enum amdgpu_int_thermal_type {
>  enum amdgpu_runpm_mode {
>  	AMDGPU_RUNPM_NONE,
>  	AMDGPU_RUNPM_PX,
> +	AMDGPU_RUNPM_GMUX,
>  	AMDGPU_RUNPM_BOCO,
>  	AMDGPU_RUNPM_BACO,
>  	AMDGPU_RUNPM_BAMACO,
> 

-- 
 i.