linux-kernel - Re: [PATCH v9 0/7] Enable L2 cache support on Exynos4210/4x12 SoCs

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Message-id: <54783899.2060604@samsung.com>
Date:	Fri, 28 Nov 2014 09:55:53 +0100
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Tomasz Figa <tomasz.figa@...il.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-samsung-soc@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Olof Johansson <olof@...om.net>,
	Kukjin Kim <kgene.kim@...sung.com>, lauraa@...eaurora.org,
	linux-omap@...r.kernel.org, linus.walleij@...aro.org,
	tony@...mide.com, drake@...lessm.com, loeliger@...il.com,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v9 0/7] Enable L2 cache support on Exynos4210/4x12 SoCs

Hello,

On 2014-11-27 23:51, Russell King - ARM Linux wrote:
> On Mon, Nov 17, 2014 at 12:48:22PM +0100, Marek Szyprowski wrote:
>> This is an updated patchset, which intends to add support for L2 cache
>> on Exynos4 SoCs on boards running under secure firmware, which requires
>> certain initialization steps to be done with help of firmware, as
>> selected registers are writable only from secure mode.
>>
>> First four patches extend existing support for secure write in L2C driver
>> to account for design of secure firmware running on Exynos. Namely:
>>   1) direct read access to certain registers is needed on Exynos, because
>>      secure firmware calls set several registers at once,
>>   2) not all boards are running secure firmware, so .write_sec callback
>>      needs to be installed in Exynos firmware ops initialization code,
>>   3) write access to {DATA,TAG}_LATENCY_CTRL registers fron non-secure world
>>      is not allowed and so must use l2c_write_sec as well,
>>   4) on certain boards, default value of prefetch register is incorrect
>>      and must be overridden at L2C initialization.
>> For boards running with firmware that provides access to individual
>> L2C registers this series should introduce no functional changes. However
>> since the driver is widely used on other platforms I'd like to kindly ask
>> any interested people for testing.
>>
>> Further three patches add implementation of .write_sec and .configure
>> callbacks for Exynos secure firmware and necessary DT nodes to enable
>> L2 cache.
>>
>> Changes in this version tested on Exynos4412-based TRATS2 and OdroidU3+
>> boards (both with secure firmware). There should be no functional change
>> for Exynos boards running without secure firmware. I do not have access
>> to affected non-Exynos boards, so I could not test on them.
> So, I applied this series, and now I get a conflicts between my tree and
> arm-soc for:
>
> arch/arm/mach-exynos/firmware.c
> arch/arm/mach-exynos/sleep.S
>
> So, I'm going to un-stage the exynos bits, and we'll have to work out
> some way to handle those.

I've already pointed that those patches depend on other previously merged to
exynos and arm-soc trees, but both Arnd and Kukjin said that those patch 
series
should go via your kernel tree:

https://lkml.org/lkml/2014/11/15/158

That's why in v9 I rebased patches once again onto vanilla v3.18-rc4 and 
uploaded
to your patch tracker. I see the following two possibilities to get them 
merged:

1. Merge patches to rmk tree and resolve the merge conflict. The 
conflict IS quite
easy to resolve - both trees, arm-soc and rmk only adds some code and 
the goal is
simply to have both chunks added.

2. Merge the previous version (v8 from the above link) to arm-soc tree, 
where it
applies cleanly on for-next, preferably with Russell's Acked-by.

Arnd, Russell: which approach do you prefer? How can I help to get it 
merged?

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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