From: swarren@wwwdotorg.org (Stephen Warren)
Date: Mon, 12 Nov 2012 09:36:15 -0700
Subject: [PATCH] ARM: tegra: retain L2 content over CPU suspend/resume
In-Reply-To: <1352693437.19251.9.camel@jlo-ubuntu-64.nvidia.com>
References: <1352194377-6209-1-git-send-email-josephl@nvidia.com>
 <509D7BA1.506@wwwdotorg.org>
 <1352693437.19251.9.camel@jlo-ubuntu-64.nvidia.com>
Message-ID: <50A1257F.8090003@wwwdotorg.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 11/11/2012 09:10 PM, Joseph Lo wrote:
> On Sat, 2012-11-10 at 05:54 +0800, Stephen Warren wrote:
>> On 11/06/2012 02:32 AM, Joseph Lo wrote:
>>> The L2 RAM is in different power domain from the CPU cluster. So the
>>> L2 content can be retained over CPU suspend/resume. To do that, we
>>> need to disable L2 after the MMU is disabled, and enable L2 before
>>> the MMU is enabled. But the L2 controller is in the same power domain
>>> with the CPU cluster. We need to restore it's settings and re-enable
>>> it after the power be resumed.
>>
>> This doesn't compile:
>>
>> arch/arm/mach-tegra/headsmp.S: Assembler messages:
>> arch/arm/mach-tegra/headsmp.S:119: Error: undefined symbol L2X0_CTRL_EN
>> used as an immediate value
>> arch/arm/mach-tegra/headsmp.S:119: Error: undefined symbol L2X0_CTRL_EN
>> used as an immediate value
> 
> Ah, sorry for mention that.
> This patch was depended on "07bd005 ARM: 7547/1: cache-l2x0: add support
> for Aurora L2 cache ctrl" and only showed up after "next-20121024". The
> definition of "L2X0_CTRL_EN" was been introduced in that patch.
> 
> Should I re-send a patch that based on tegra "for-next" branch that will
> change L2X0_CTRL_EN to 0x1? Sorry for inconvenience.

That's probably simplest. Perhaps rather than just replacing the #define
with a literal, do:

#ifndef L2X0_CTRL_EN
#define L2X0_CTRL_EN                   1
#endif

So that we can simply remove that ifdef block later once we know patch
7547 is present.