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From: Jon Masters <jcm@redhat.com>
To: Hanjun Guo <guohanjun@huawei.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Hanjun Guo <hanjun.guo@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Olof Johansson <olof@lixom.net>,
	Grant Likely <grant.likely@linaro.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Graeme Gregory <graeme.gregory@linaro.org>,
	Sudeep Holla <Sudeep.Holla@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Mark Brown <broonie@kernel.org>, Robert Richter <rric@kernel.org>,
	Timur Tabi <timur@codeaurora.org>,
	Ashwin Chaugule <ashwinc@codeaurora.org>,
	suravee.suthikulpanit@amd.com, linux-acpi@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linaro-acpi@lists.linaro.org,
	Tomasz Nowicki <tomasz.nowicki@linaro.org>,
	Zhangdianfang <zhangdianfang@huawei.com>
Subject: Re: [update][PATCH v10 06/21] ACPI / sleep: Introduce CONFIG_ACPI_GENERIC_SLEEP
Date: Tue, 17 Mar 2015 01:59:30 -0400	[thread overview]
Message-ID: <5507C2C2.1090509@redhat.com> (raw)
In-Reply-To: <5507A91A.1090206@huawei.com>

On 03/17/2015 12:10 AM, Hanjun Guo wrote:
> On 2015/3/17 11:23, Rafael J. Wysocki wrote:
>> On Tuesday, March 17, 2015 10:36:47 AM Hanjun Guo wrote:

>> Well, almost.  There is one problem with that, becuase sleep.c contains code
>> outside of the ACPI_SLEEP-dependent blocks.  That code is used for powering
>> off ACPI platforms.
>>
>> I guess you don't want that code on ARM too, right?
> 
> Yes, you are right.

>> Perhaps we can use ACPI_REDUCED_HARDWARE_ONLY for that?  ARM64 will be the
> 
> Sorry, I can't fully understand your intention here, could you please
> explain it more?
> 
> Let me guess a little bit. Do you mean use ACPI_REDUCED_HARDWARE_ONLY for
> powering off ACPI platforms? if so, I guess it's not a good idea, ACPI spec
> only says that S4BIOS is not supported on HW-reduced ACPI platforms, S5
> has no such limitation, if I miss something here, please let me know.

If helpful to the discussion, current SBBR (Server Base Boot
Requirements[0]) design guidance is that for power off itself, we will
prefer calling an EFI Runtime Service (that will preferentially call an
PSCI - ARM Power State Coordination Interface - Secure Monitor Call (SMC
- think SMI-like) internally to perform the shutdown/reboot) for the
action of powering off or resetting 64-bit ARM SBBR platforms.

Therefore if the alternative of an ACPI-based power off solution were
not initially supported, I don't think it would have much practical
impact, and it could be addressed after the initial support merged.

That's just my $0.02.

Jon.

[0] The Server Base Boot Requirements are the platform specification we
created for 64-bit ARM servers. They mandate the use of EFI and ACPI in
compliant platforms:
http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf


  reply	other threads:[~2015-03-17  5:59 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-13  8:14 Hanjun Guo
2015-03-13 21:49 ` Rafael J. Wysocki
2015-03-16 12:14   ` Hanjun Guo
2015-03-16 23:15     ` Rafael J. Wysocki
2015-03-17  1:08       ` Hanjun Guo
2015-03-17  2:28         ` Rafael J. Wysocki
2015-03-17  2:36           ` Hanjun Guo
2015-03-17  3:23             ` Rafael J. Wysocki
2015-03-17  4:10               ` Hanjun Guo
2015-03-17  5:59                 ` Jon Masters [this message]
2015-03-17  6:31                   ` Hanjun Guo
2015-03-17 14:33                 ` Rafael J. Wysocki
2015-03-18  1:56                   ` Hanjun Guo
2015-03-17 12:35               ` Lorenzo Pieralisi
     [not found]                 ` <CAGHbJ3DhUB688K7ooT7ai=2QjRp7S+_E_Y+a+GupeTvjR5omMg@mail.gmail.com>
2015-03-17 14:29                   ` [PATCH] ACPI / sleep: Drop acpi_suspend() which is not used Rafael J. Wysocki
2015-03-17 14:24                     ` Lorenzo Pieralisi
2015-03-18  1:17                     ` Hanjun Guo
2015-03-17 14:30                 ` [update][PATCH v10 06/21] ACPI / sleep: Introduce CONFIG_ACPI_GENERIC_SLEEP Rafael J. Wysocki

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