Re: [PATCH 1/3] ACPI / idle: Move idle_boot_override out of the arch directory

From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Sudeep Holla <Sudeep.Holla@arm.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Will Deacon <Will.Deacon@arm.com>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"grant.likely@linaro.org" <grant.likely@linaro.org>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	Olof Johansson <olof@lixom.net>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"rob.herring@calxeda.com" <rob.herring@calxeda.com>,
	Mark Rutland <Mark.Rutland@arm.com>,
	Jon Masters <jonathan@jonmasters.org>,
	"patches@linaro.org" <patches@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
	"linaro-acpi@lists.linaro.org" <linaro-acpi@lists.linaro.org>
Subject: Re: [PATCH 1/3] ACPI / idle: Move idle_boot_override out of the arch directory
Date: Sat, 18 Jan 2014 14:47:43 +0100	[thread overview]
Message-ID: <5375666.26CZK1LlZA@vostro.rjw.lan> (raw)
In-Reply-To: <52D9FA72.5020505@linaro.org>

On Saturday, January 18, 2014 11:52:18 AM Hanjun Guo wrote:
> On 2014-1-18 11:45, Hanjun Guo wrote:
> > On 2014-1-17 20:06, Sudeep Holla wrote:
> >> On 17/01/14 02:03, Hanjun Guo wrote:
> >>> Move idle_boot_override out of the arch directory to be a single enum
> >>> including both platforms values, this will make it rather easier to
> >>> avoid ifdefs around which definitions are for which processor in
> >>> generally used ACPI code.
> >>>
> >>> IDLE_FORCE_MWAIT for IA64 is not used anywhere, so romove it.
> >>>
> >>> No functional change in this patch.
> >>>
> >>> Suggested-by: Alan <gnomes@lxorguk.ukuu.org.uk>
> >>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> >>> ---
> [...]
> >>> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> >>> index 03e235ad..e324561 100644
> >>> --- a/include/linux/cpu.h
> >>> +++ b/include/linux/cpu.h
> >>> @@ -220,6 +220,14 @@ void cpu_idle(void);
> >>>  
> >>>  void cpu_idle_poll_ctrl(bool enable);
> >>>  
> >>> +enum idle_boot_override {
> >>> +	IDLE_NO_OVERRIDE = 0,
> >>> +	IDLE_HALT,
> >>> +	IDLE_NOMWAIT,
> >>> +	IDLE_POLL,
> >>> +	IDLE_POWERSAVE_OFF
> >>> +};
> >>> +
> >>
> >> I do understand the idea behind this change, but IMO HALT and MWAIT are x86
> >> specific and may not make sense for other architectures.
> > 
> > yes, this is the strange part, the value is arch-dependent.
> > 
> >>
> >> It will also require every architecture using ACPI to export
> >> boot_option_idle_override which may not be really required.
> > 
> > so, how about forget this patch and move boot_option_idle_override
> > related code into arch directory such as arch/x86/acpi/boot.c for
> > x86?
> 
> The general idea is that we can move all the arch-dependent codes
> in ACPI driver to arch directory, then make codes in drivers/acpi/
> arch independent.

Well, MWAIT is arch-dependent, so I'm not sure how IDLE_NOMWAIT fits into
include/linux/cpu.h?

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.