linux-kernel - Re: [PATCH v4 3/6] ARM: Add Krait L2 accessor functions

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Message-ID: <52CC8947.7020900@codeaurora.org>
Date:	Tue, 07 Jan 2014 15:09:59 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Borislav Petkov <bp@...en8.de>
CC:	linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Mark Rutland <mark.rutland@....com>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH v4 3/6] ARM: Add Krait L2 accessor functions

On 01/07/14 15:07, Borislav Petkov wrote:
> On Mon, Dec 30, 2013 at 12:14:14PM -0800, Stephen Boyd wrote:
>> Krait CPUs have a handful of L2 cache controller registers that
>> live behind a cp15 based indirection register. First you program
>> the indirection register (l2cpselr) to point the L2 'window'
>> register (l2cpdr) at what you want to read/write.  Then you
>> read/write the 'window' register to do what you want. The
>> l2cpselr register is not banked per-cpu so we must lock around
>> accesses to it to prevent other CPUs from re-pointing l2cpdr
>> underneath us.
>>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Russell King <linux@....linux.org.uk>
>> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
>> ---
>>  arch/arm/common/Kconfig                   |  3 ++
>>  arch/arm/common/Makefile                  |  1 +
>>  arch/arm/common/krait-l2-accessors.c      | 58 +++++++++++++++++++++++++++++++
>>  arch/arm/include/asm/krait-l2-accessors.h | 20 +++++++++++
> I'm no ARM guy but out of curiosity, why is this code not part of the
> krait edac driver? IOW, is there a compelling reason for it to be in
> arch/arm/common/?

This is used for more than just the edac driver. In the future, we'll
need this for the cpufreq driver and the l2 performance monitor driver.
I suppose I could have stated that in the commit text.

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