linux-kernel - Re: [PATCH 1/4] arm: topology: remove cpu

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Message-ID: <303d3f7b-5d64-e13a-c4f9-dd575958cafa@arm.com>
Date:   Wed, 6 Sep 2017 12:43:31 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        LAK <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
        linux-renesas-soc@...r.kernel.org,
        Russell King <linux@...linux.org.uk>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Juri Lelli <juri.lelli@....com>
Subject: Re: [PATCH 1/4] arm: topology: remove cpu_efficiency

Hi Vincent,

On 04/09/17 08:49, Vincent Guittot wrote:
> Hi Dietmar,
> 
> Removing cpu effificiency table looks good to me. Nevertheless, i have
> some comments below for this patch.

Thanks for the review!

> On 30 August 2017 at 16:41, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
>> Remove the 'cpu_efficiency/clock-frequency dt property' based solution
>> to set cpu capacity which was only working for Cortex-A15/A7 arm
>> big.LITTLE systems.
>>
>> I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is
>> shared between arm and arm64 and works for every big.LITTLE system no
>> matter which core types it consists of.
>>
>> Cc: Russell King <linux@....linux.org.uk>
>> Cc: Vincent Guittot <vincent.guittot@...aro.org>
>> Cc: Juri Lelli <juri.lelli@....com>
>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
>> ---
>>  arch/arm/kernel/topology.c | 113 ++-------------------------------------------
>>  1 file changed, 3 insertions(+), 110 deletions(-)

[...]

>> @@ -115,73 +70,13 @@ static void __init parse_dt_topology(void)
>>                         of_node_put(cn);
>>                         continue;
> 
> AFAICT, this continue is now useless as it was there to skipe the cpu
> table efficiency method

You're right ... will remove it.

[...]

>> -       if (cap_from_dt)
>> -               topology_normalize_cpu_scale();
> 
> Why have you moved the call to topology_normalize_cpu_scale() from
> parse_dt_topology() to update_cpu_capacity() ?

Didn't move it ? It's still called from parse_dt_topology().

> You should keep it in parse_dt_topology() as itis part of the dt
> parsing sequence

Yes, this should be the case.

[...]

>> -/*
>> - * Look for a customed capacity of a CPU in the cpu_capacity table during the
>> - * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
>> - * function returns directly for SMP system.
>> - */
>> -static void update_cpu_capacity(unsigned int cpu)
>> -{
>> -       if (!cpu_capacity(cpu) || cap_from_dt)
>> -               return;
>> -
>> -       topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity);
>> -
>> -       pr_info("CPU%u: update cpu_capacity %lu\n",
>> -               cpu, topology_get_cpu_scale(NULL, cpu));
>> +       topology_normalize_cpu_scale();
>>  }
> 
> You can probably just removed update_cpu_capacity()

I did remove update_cpu_capacity(). Maybe the patch layout is confusing?

[...]