linux-kernel - Re: [PATCH v11 1/7] ACPI: scan: Obtain device's desired enumeration power state

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Date:   Thu, 11 Feb 2021 20:10:11 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-i2c <linux-i2c@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Mani, Rajmohan" <rajmohan.mani@...el.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Chiranjeevi Rapolu <chiranjeevi.rapolu@...el.com>,
        Hyungwoo Yang <hyungwoo.yang@...el.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>
Subject: Re: [PATCH v11 1/7] ACPI: scan: Obtain device's desired enumeration
 power state

On Thu, Feb 11, 2021 at 12:08 AM Sakari Ailus
<sakari.ailus@...ux.intel.com> wrote:
>
> Store a device's desired enumeration power state in struct
> acpi_device_power during acpi_device object's initialisation.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> ---
>  drivers/acpi/scan.c     | 4 ++++
>  include/acpi/acpi_bus.h | 1 +
>  2 files changed, 5 insertions(+)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index a184529d8fa40..6a9b4a92c4f66 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -987,6 +987,7 @@ static void acpi_bus_init_power_state(struct acpi_device *device, int state)
>
>  static void acpi_bus_get_power_flags(struct acpi_device *device)
>  {
> +       unsigned long long dse = ACPI_STATE_D0;
>         u32 i;
>
>         /* Presence of _PS0|_PR0 indicates 'power manageable' */
> @@ -1008,6 +1009,9 @@ static void acpi_bus_get_power_flags(struct acpi_device *device)
>         if (acpi_has_method(device->handle, "_DSW"))
>                 device->power.flags.dsw_present = 1;
>
> +       acpi_evaluate_integer(device->handle, "_DSE", NULL, &dse);

As a matter of notice, it is likely that this object will be called
_DSC (Deepest State for Configuration) which better reflects its
function.

The ACPI ECR introducing it will be sent next week if all goes well.

Thanks!

> +       device->power.state_for_enumeration = dse;
> +
>         /*
>          * Enumerate supported power management states
>          */
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 02a716a0af5d4..becfc9f57002b 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -276,6 +276,7 @@ struct acpi_device_power {
>         int state;              /* Current state */
>         struct acpi_device_power_flags flags;
>         struct acpi_device_power_state states[ACPI_D_STATE_COUNT];      /* Power states (D0-D3Cold) */
> +       u8 state_for_enumeration; /* Maximum power state for enumeration */
>  };
>
>  /* Performance Management */
> --
> 2.20.1
>