linux-kernel - Re: [PATCH v4 7/8] ARM: dts: Exynos5422: fix OPP tables

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Message-id: <56677701.10809@samsung.com>
Date:	Wed, 09 Dec 2015 09:34:09 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Javier Martinez Canillas <javier@....samsung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Thomas Abraham <thomas.ab@...sung.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Mike Turquette <mturquette@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Ben Gamari <ben@...rt-cactus.org>
Cc:	Tomasz Figa <tomasz.figa@...il.com>,
	Lukasz Majewski <l.majewski@...sung.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Kevin Hilman <khilman@...aro.org>,
	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
	Anand Moon <linux.amoon@...il.com>,
	linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 7/8] ARM: dts: Exynos5422: fix OPP tables

On 08.12.2015 22:41, Javier Martinez Canillas wrote:
> Hello Krzysztof,
> 
> On 12/08/2015 05:13 AM, Krzysztof Kozlowski wrote:
>> On 08.12.2015 03:18, Bartlomiej Zolnierkiewicz wrote:
>>> From: Ben Gamari <ben@...rt-cactus.org>
>>>
>>> The Exynos 5422 is identical to the 5800 except for the fact that it
>>> boots from the A7 cores. Consequently, the core numbering is different:
>>> cores 0-3 are A7s whereas 4-7 are A15s.
>>>
>>> We can reuse the device tree of the 5800 for the 5422 but we must take
>>> care to override the OPP tables and CPU clocks.  These are otherwise
>>> inherited from the exynos5800 devicetree, which has the CPU clusters
>>> reversed compared to the 5422. This results in the A15 cores only
>>> reaching 1.4GHz, the maximum rate of the KFC clock.
>>>
>>> Cc: Javier Martinez Canillas <javier@....samsung.com>
>>> Signed-off-by: Ben Gamari <ben@...rt-cactus.org>
>>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>>> ---
>>>  arch/arm/boot/dts/exynos5422-cpus.dtsi | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>
>> This looks like a very-non-atomic way of handling a change. You added
>> opp tables to exynos5420 before so at that time they will be applied to
>> Odroid XU3 family which uses different CPU order. After that you are
>> fixing the tables to proper CPU order. Direct bisectability probably
>> won't be an issue because all of DTS would go to separate branch... but
>> the logic behind confuses.
>>
> 
> Agreed.
> 
>> I think this should be squashed into 3/8.
>>
> 
> I think the patch should be split in two changes, the CPUs device nodes
> having the wrong clock for clusters is a bug and has to be fixed in a
> patch before adding the OPP tables and the OPP tables changes should be
> separated and merged with patch 3/8 as you suggest.

I don't get the point about wrong clock (bug). Where is the bug? Beside
of course what was introduced in 3/8 and it is not valid for reversed
cluster order.

Best regards,
Krzysztof

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