linux-kernel - Re: [PATCH v3 0/2] arm: remove cpu

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Message-ID: <316592bf-5aa4-3847-79cd-3a26adbb1231@arm.com>
Date:   Tue, 24 Oct 2017 15:31:54 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Juri Lelli <juri.lelli@...il.com>
Subject: Re: [PATCH v3 0/2] arm: remove cpu_efficiency

Hi Russel,

Thanks for the review!

On 24/10/17 11:52, Russell King - ARM Linux wrote:
> On Tue, Oct 24, 2017 at 11:27:16AM +0100, Dietmar Eggemann wrote:
>> With the dt related patches for exynos and renesas now in the
>> appropriated for-next branches for v4.15 there are no Cortex-A15/A7 arm
>> big.LITTLE systems left relying on the 'cpu_efficiency/clock-frequency
>> dt property' based solution anymore.
> 
> This is way too early to remove support for something that has been
> in place since 2012.  As you've just shown, people are using it with
> DT files today.  We don't know how long people will persist using
> older files, and we don't know whether there are DT files out in the
> wild that we don't know about.

Understood. But do we really care about out of tree dt files?

In case the mentioned exynos and renesas Cortex-A15/A7 platforms change
to using 'capacity-dmips-mhz' in v4.15 there shouldn't be any
Cortex-A15/A7 platforms in mainline left using the cpu_efficiency
solution anymore.

> Our general rule is that we maintain compatibility for older DT.

OK.

> NAK.

Then I still send out [2/2] separately.