[PATCH v4 02/11] PCI/ACPI: Per root port allow one Aux power limit request

[Ilpo Järvinen]

On Thu, 29 May 2025, Badal Nilawar wrote:

> For given root port allow one Aux power limit request.
> 
> Cc: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> Cc: Anshuman Gupta <anshuman.gupta at intel.com>
> Signed-off-by: Badal Nilawar <badal.nilawar at intel.com>
> ---
>  drivers/acpi/scan.c     |  1 +
>  drivers/pci/pci-acpi.c  | 25 ++++++++++++++++++++++++-
>  include/acpi/acpi_bus.h |  2 ++
>  3 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index fb1fe9f3b1a3..9ae7be9db01a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -745,6 +745,7 @@ int acpi_device_add(struct acpi_device *device)
>  	INIT_LIST_HEAD(&device->physical_node_list);
>  	INIT_LIST_HEAD(&device->del_list);
>  	mutex_init(&device->physical_node_lock);
> +	mutex_init(&device->power.aux_pwr_lock);

Hi,

mutex_destroy() also exists but I don't find any added by this patch?
I think the pre-existing mutex might also have this same problem.

>  
>  	mutex_lock(&acpi_device_lock);
>  
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 87f30910a5f1..d33efba4ca94 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -1451,6 +1451,7 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
>  	union acpi_object *out_obj;
>  	acpi_handle handle;
>  	int result, ret = -EINVAL;
> +	struct acpi_device *adev;
>  
>  	if (!dev || !retry_interval)
>  		return -EINVAL;
> @@ -1464,11 +1465,27 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
>  		return -ENODEV;
>  	}
>  
> +	adev = ACPI_COMPANION(&dev->dev);
> +	if (!adev)
> +		return -EINVAL;
> +
> +	mutex_lock(&adev->power.aux_pwr_lock);
> +
> +	/* Check if aux power already granted */
> +	if (adev->power.aux_power_limit) {
> +		pci_info(dev, "D3cold Aux Power request already granted: %u mW\n",
> +			 adev->power.aux_power_limit);
> +		mutex_unlock(&adev->power.aux_pwr_lock);
> +		return -EPERM;
> +	}
> +
>  	out_obj = acpi_evaluate_dsm_typed(handle, &pci_acpi_dsm_guid, 4,
>  					  DSM_PCI_D3COLD_AUX_POWER_LIMIT,
>  					  &in_obj, ACPI_TYPE_INTEGER);
> -	if (!out_obj)
> +	if (!out_obj) {
> +		mutex_unlock(&adev->power.aux_pwr_lock);
>  		return -EINVAL;
> +	}
>  
>  	result = out_obj->integer.value;
>  	if (retry_interval)
> @@ -1478,14 +1495,17 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
>  	case 0x0:
>  		pci_dbg(dev, "D3cold Aux Power %u mW request denied\n",
>  			requested_power);
> +		adev->power.aux_power_limit = 0;
>  		break;
>  	case 0x1:
>  		pci_info(dev, "D3cold Aux Power request granted: %u mW\n",
>  			 requested_power);
> +		adev->power.aux_power_limit = requested_power;
>  		ret = 0;
>  		break;
>  	case 0x2:
>  		pci_info(dev, "D3cold Aux Power: Main power won't be removed\n");
> +		adev->power.aux_power_limit = 0;
>  		ret = -EBUSY;
>  		break;
>  	default:
> @@ -1500,9 +1520,12 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power,
>  			pci_err(dev, "D3cold Aux Power: Reserved or unsupported response: 0x%x\n",
>  				result);
>  		}
> +		adev->power.aux_power_limit = 0;
>  		break;
>  	}
>  
> +	mutex_unlock(&adev->power.aux_pwr_lock);
> +
>  	ACPI_FREE(out_obj);
>  	return ret;
>  }
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index aad1a95e6863..c4ce3d84be00 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -294,6 +294,8 @@ struct acpi_device_power {
>  	struct acpi_device_power_flags flags;
>  	struct acpi_device_power_state states[ACPI_D_STATE_COUNT];	/* Power states (D0-D3Cold) */
>  	u8 state_for_enumeration; /* Deepest power state for enumeration */
> +	u32 aux_power_limit;		/* aux power limit granted by bios */
> +	struct mutex aux_pwr_lock;	/* prevent concurrent aux power limit requests */
>  };
>  
>  struct acpi_dep_data {
> 

-- 
 i.