linux-kernel - Re: [PATCH v3 2/6] ACPI: scan: Add function to fetch dependent of acpi device

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Message-ID: <CAHp75VeK-0gJ195mXjuZDPLKD4ROVKfFaoWw97yJ1NXpK1QVWg@mail.gmail.com>
Date:   Mon, 22 Feb 2021 15:41:21 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Daniel Scally <djrscally@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Tomasz Figa <tfiga@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Rajmohan Mani <rajmohan.mani@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Wolfram Sang <wsa@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        kieran.bingham+renesas@...asonboard.com,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>, me@...wu.ch,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        devel@...ica.org
Subject: Re: [PATCH v3 2/6] ACPI: scan: Add function to fetch dependent of
 acpi device

On Mon, Feb 22, 2021 at 3:11 PM Daniel Scally <djrscally@...il.com> wrote:
>
> In some ACPI tables we encounter, devices use the _DEP method to assert
> a dependence on other ACPI devices as opposed to the OpRegions that the
> specification intends. We need to be able to find those devices "from"
> the dependee, so add a callback and a wrapper to walk over the
> acpi_dep_list and return the dependent ACPI device.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Nit-picks below as usual :-)

> Signed-off-by: Daniel Scally <djrscally@...il.com>
> ---
> Changes in v3:
>         - Switched from a standalone function to a callback passed to
>           acpi_walk_dep_device_list().
>
>  drivers/acpi/scan.c     | 34 ++++++++++++++++++++++++++++++++++
>  include/acpi/acpi_bus.h |  1 +
>  2 files changed, 35 insertions(+)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index c9e4190316ef..55626925261c 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2093,6 +2093,21 @@ static void acpi_bus_attach(struct acpi_device *device, bool first_pass)
>                 device->handler->hotplug.notify_online(device);
>  }
>
> +static int __acpi_dev_get_dependent_dev(struct acpi_dep_data *dep, void *data)
> +{
> +       struct acpi_device *adev;
> +       int ret;
> +
> +       ret = acpi_bus_get_device(dep->consumer, &adev);
> +       if (ret)
> +               /* If we don't find an adev then we want to continue parsing */
> +               return 0;
> +
> +       *(struct acpi_device **)data = adev;

Hmm... I'm wondering if
  *(void **data) = adev;
will compile and work.

But on second thought the current code is more specific and explicit,
which is good.

> +
> +       return 1;
> +}
> +
>  static int __acpi_dev_flag_dependency_met(struct acpi_dep_data *dep,
>                                           void *data)
>  {
> @@ -2145,6 +2160,25 @@ void acpi_dev_flag_dependency_met(acpi_handle handle)
>  }
>  EXPORT_SYMBOL_GPL(acpi_dev_flag_dependency_met);
>
> +/**
> + * acpi_dev_get_dependent_dev - Return ACPI device dependent on @adev
> + * @adev: Pointer to the dependee device
> + *
> + * Returns the first &struct acpi_device which declares itself dependent on
> + * @adev via the _DEP buffer, parsed from the acpi_dep_list.
> + */

> +struct acpi_device *
> +acpi_dev_get_dependent_dev(struct acpi_device *supplier)

I believe it will be okay to have it on one line

> +{
> +       struct acpi_device *adev = NULL;

> +       acpi_walk_dep_device_list(supplier->handle,
> +                                 __acpi_dev_get_dependent_dev, &adev);

Ditto.

> +       return adev;
> +}
> +EXPORT_SYMBOL_GPL(acpi_dev_get_dependent_dev);
> +
>  /**
>   * acpi_bus_scan - Add ACPI device node objects in a given namespace scope.
>   * @handle: Root of the namespace scope to scan.
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 91172af3a04d..5b14a9ae4ed5 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -690,6 +690,7 @@ static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
>  bool acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, const char *uid2);
>
>  void acpi_dev_flag_dependency_met(acpi_handle handle);
> +struct acpi_device *acpi_dev_get_dependent_dev(struct acpi_device *supplier);
>  struct acpi_device *
>  acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const char *uid, s64 hrv);
>  struct acpi_device *
> --
> 2.25.1
>


-- 
With Best Regards,
Andy Shevchenko