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

[Rafael J. Wysocki]

On Thu, May 29, 2025 at 1:14 PM Badal Nilawar <badal.nilawar at intel.com> 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);
>
>         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);

Use a mutex locking guard for this new lock, please.

> +
> +       /* 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;

Maybe -EALREADY?

> +       }
> +
>         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 {
> --
> 2.34.1
>