linux-kernel - Re: [PATCH 1/2] acpi: Add acpi_init

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Date:   Sat, 24 Jul 2021 12:51:07 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Michael Bottini <michael.a.bottini@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, irenic.rajneesh@...il.com,
        David Box <david.e.box@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH 1/2] acpi: Add acpi_init_properties to ACPI driver code

On Fri, Jul 23, 2021 at 10:25 PM Michael Bottini
<michael.a.bottini@...ux.intel.com> wrote:
>
> Some products in the field, like Intel Rocket Lake systems, contain
> AML code that can modify _DSD properties after they have been
> evaluated by ACPI init code.

That is directly against the spec.

> Therefore, there is a need for drivers
> to be able to reevaluate _DSDs so that the updated property values can
> be read. Export acpi_init_properties() for this purpose.

I'm not sure.  By the spec, the OS need not evaluate _DSD for a given
device more than once.

> Signed-off-by: Michael Bottini <michael.a.bottini@...ux.intel.com>
> ---
>  drivers/acpi/property.c | 1 +
>  include/linux/acpi.h    | 6 ++++++
>  2 files changed, 7 insertions(+)
>
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index e312ebaed8db..2c1f8cf1a8f0 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -432,6 +432,7 @@ void acpi_init_properties(struct acpi_device *adev)
>         if (!adev->data.pointer)
>                 acpi_extract_apple_properties(adev);
>  }
> +EXPORT_SYMBOL(acpi_init_properties);

EXPORT_SyMBOL_GPL(), please.

>  static void acpi_destroy_nondev_subnodes(struct list_head *list)
>  {
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 72e4f7fd268c..57defc3bc9b9 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -716,6 +716,8 @@ static inline u64 acpi_arch_get_root_pointer(void)
>
>  int acpi_get_local_address(acpi_handle handle, u32 *addr);
>
> +void acpi_init_properties(struct acpi_device *adev);
> +
>  #else  /* !CONFIG_ACPI */
>
>  #define acpi_disabled 1
> @@ -976,6 +978,10 @@ static inline int acpi_get_local_address(acpi_handle handle, u32 *addr)
>         return -ENODEV;
>  }
>
> +static inline void acpi_init_properties(struct acpi_device *adev)
> +{
> +}
> +
>  #endif /* !CONFIG_ACPI */
>
>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
> --
> 2.25.1
>