From mboxrd@z Thu Jan  1 00:00:00 1970
From: jcm@redhat.com (Jon Masters)
Date: Fri, 12 Sep 2014 15:43:36 -0400
Subject: [PATCH v4 05/18] ARM64 / ACPI: Introduce sleep-arm.c
In-Reply-To: <1410530416-30200-6-git-send-email-hanjun.guo@linaro.org>
References: <1410530416-30200-1-git-send-email-hanjun.guo@linaro.org>
 <1410530416-30200-6-git-send-email-hanjun.guo@linaro.org>
Message-ID: <54134CE8.8070506@redhat.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 09/12/2014 10:00 AM, Hanjun Guo wrote:
> From: Graeme Gregory <graeme.gregory@linaro.org>
> 
> ACPI 5.1 does not currently support S states for ARM64 hardware but
> ACPI code will call acpi_target_system_state() for device power
> managment, so introduce sleep-arm.c to allow other drivers to function
> until S states are defined.

Aside: ACPI5.1 does define the Platform Communication Channel and CPC
(Collaborative Processor Performance Control). Some details need to be
fleshed out there for practical 64-bit ARMv8 server systems, but the
underpinnings and mechanisms are in place in the 5.1 specification that
can be built upon over time to achieve practical S-State equivalence.

Jon.