linux-kernel - Re: [PATCH] cpuidle: Move cpuidle driver forward before acpi driver in Makefile

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Message-ID: <CAJZ5v0gsHPav5Ax6+9OMmeApqn7qdJPQmo5MMh=ba6Rtj5NnQA@mail.gmail.com>
Date:   Wed, 13 Jul 2022 19:53:13 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Dapeng Mi <dapeng1.mi@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Bart Van Assche <bvanassche@....org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] cpuidle: Move cpuidle driver forward before acpi driver
 in Makefile

On Wed, Jul 13, 2022 at 10:21 AM Dapeng Mi <dapeng1.mi@...el.com> wrote:
>
> As long as Kconfig ACPI_PROCESSOR is enabled, ACPI_PROCESSOR would
> select ACPI_PROCESSOR_IDLE and acpi_idle driver is enabled. But
> in current driver loading order acpi_idle driver is always loaded
> before cpuidle_haltpoll driver. This leads to cpuidle_hatpoll driver
> has no chance to be loaded when it's enabled.
>
> Thus, move cpuidle driver forward before acpi driver and make
> cpuidle-hatpoll driver has a chance to be run when it's enabled.
>
> Signed-off-by: Dapeng Mi <dapeng1.mi@...el.com>
> ---
>  drivers/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/Makefile b/drivers/Makefile
> index 9a30842b22c5..921ed481b520 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -26,6 +26,7 @@ obj-y                         += idle/
>  # IPMI must come before ACPI in order to provide IPMI opregion support
>  obj-y                          += char/ipmi/
>
> +obj-$(CONFIG_CPU_IDLE)         += cpuidle/
>  obj-$(CONFIG_ACPI)             += acpi/
>
>  # PnP must come after ACPI since it will eventually need to check if acpi
> @@ -126,7 +127,6 @@ obj-$(CONFIG_EDAC)          += edac/
>  obj-$(CONFIG_EISA)             += eisa/
>  obj-$(CONFIG_PM_OPP)           += opp/
>  obj-$(CONFIG_CPU_FREQ)         += cpufreq/
> -obj-$(CONFIG_CPU_IDLE)         += cpuidle/
>  obj-y                          += mmc/
>  obj-y                          += ufs/
>  obj-$(CONFIG_MEMSTICK)         += memstick/
> --

Well, this change doesn't guarantee loading haltpoll before ACPI idle.

Also what if haltpoll is enabled, but the user wants ACPI idle?