linux-kernel - Re: [PATCH 2/2] ACPI: let BIOS fall back to legacy handling if PRM disabled

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Date:   Fri, 2 Jul 2021 13:37:58 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Aubrey Li <aubrey.li@...el.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>
Subject: Re: [PATCH 2/2] ACPI: let BIOS fall back to legacy handling if PRM disabled

On Fri, Jul 2, 2021 at 9:03 AM Aubrey Li <aubrey.li@...el.com> wrote:
>
> Based on _OSC PRM bit, BIOS can choose switch from legacy handling
> to using PRM. So if CONFIG_ACPI_PRMT is disabled, this bit should
> not be set to let BIOS fall back to the legacy handling (such as SMI).
>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Aubrey Li <aubrey.li@...ux.intel.com>
> ---
>  drivers/acpi/bus.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index 60fb6a84..30a3d4a 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -303,7 +303,9 @@ static void acpi_bus_osc_negotiate_platform_control(void)
>
>         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_HOTPLUG_OST_SUPPORT;
>         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PCLPI_SUPPORT;
> +#ifdef CONFIG_ACPI_PRMT
>         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PRM_SUPPORT;
> +#endif

What about using if (IS_ENABLED()) instead of #ifdef?

>
>  #ifdef CONFIG_ARM64
>         capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_GENERIC_INITIATOR_SUPPORT;
> --
> 2.7.4
>