linux-kernel - Re: [PATCH] ACPI / init: Switch over platform to the ACPI mode later

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Date:	Wed, 10 Jun 2015 12:38:21 +0800
From:	joeyli <jlee@...e.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Toshi Kani <toshi.kani@...com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Len Brown <len.brown@...el.com>,
	Marius Tolzmann <tolzmann@...gen.mpg.de>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Aaron Lu <aaron.lu@...el.com>, Lv Zheng <lv.zheng@...el.com>
Subject: Re: [PATCH] ACPI / init: Switch over platform to the ACPI mode later

On Wed, Jun 10, 2015 at 01:48:29AM +0200, Rafael J. Wysocki wrote:
> On Wednesday, June 03, 2015 11:13:57 AM Toshi Kani wrote:
> > On Sat, 2015-05-30 at 14:21 +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > > 
> > > Commit 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before
> > > timekeeping_init()" moved the ACPI subsystem initialization,
> > > including the ACPI mode enabling, to an earlier point in the
> > > initialization sequence, to allow the timekeeping subsystem
> > > use ACPI early.  Unfortunately, that resulted in boot regressions
> > > on some systems and the early ACPI initialization was moved toward
> > > its original position in the kernel initialization code by commit
> > > c4e1acbb35e4 "ACPI / init: Invoke early ACPI initialization later".
> > > 
> > > However, that turns out to be insufficient, as boot is still broken
> > > on the Tyan S8812 mainboard.
> > > 
> > > To fix that issue, split the ACPI early initialization code into
> > > two pieces so the majority of it still located in acpi_early_init()
> > > and the part switching over the platform into the ACPI mode goes into
> > > a new function, acpi_subsystem_init(), executed at the original early
> > > ACPI initialization spot.
> > > 
> > > That fixes the Tyan S8812 boot problem, but still allows ACPI
> > > tables to be loaded earlier which is useful to the EFI code in
> > > efi_enter_virtual_mode().
> > > 
> > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=97141
> > > Reported-and-tested-by: Marius Tolzmann <tolzmann@...gen.mpg.de>
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > 
> > Can you add comments to acpi_early_init() and acpi_subsystem_init() to
> > clarify what ACPI features are enabled at each phase, and what
> > dependency they have in the boot sequence?  (The same goes to
> > early_acpi_boot_init() and acpi_boot_init().)
> 
> OK, update follows.
> 
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: ACPI / init: Switch over platform to the ACPI mode later
> 
> Commit 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before
> timekeeping_init()" moved the ACPI subsystem initialization,
> including the ACPI mode enabling, to an earlier point in the
> initialization sequence, to allow the timekeeping subsystem
> use ACPI early.  Unfortunately, that resulted in boot regressions
> on some systems and the early ACPI initialization was moved toward
> its original position in the kernel initialization code by commit
> c4e1acbb35e4 "ACPI / init: Invoke early ACPI initialization later".
> 
> However, that turns out to be insufficient, as boot is still broken
> on the Tyan S8812 mainboard.
> 
> To fix that issue, split the ACPI early initialization code into
> two pieces so the majority of it still located in acpi_early_init()
> and the part switching over the platform into the ACPI mode goes into
> a new function, acpi_subsystem_init(), executed at the original early
> ACPI initialization spot.
> 
> That fixes the Tyan S8812 boot problem, but still allows ACPI
> tables to be loaded earlier which is useful to the EFI code in
> efi_enter_virtual_mode().
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=97141
> Fixes: 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before timekeeping_init()"
> Reported-and-tested-by: Marius Tolzmann <tolzmann@...gen.mpg.de>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Acked-by: Toshi Kani <toshi.kani@...com>
> ---
>  drivers/acpi/bus.c   |   56 +++++++++++++++++++++++++++++++++++++--------------
>  include/linux/acpi.h |    2 +
>  init/main.c          |    1 
>  3 files changed, 44 insertions(+), 15 deletions(-)

About bko#97141, I am still curious why the platform didn't set SCI_EN
in that early stage.

Thanks for Rafael's patch.

Reviewed-by: Lee, Chun-Yi <jlee@...e.com>


Regards
Joey Lee
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