linux-kernel - Re: [PATCH 6/7] arm, arm64: factorize common cpu capacity default code

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Date:   Thu, 19 Jan 2017 16:00:45 +0000
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Juri Lelli <juri.lelli@....com>, linux-kernel@...r.kernel.org
Cc:     linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, peterz@...radead.org,
        vincent.guittot@...aro.org, robh+dt@...nel.org,
        mark.rutland@....com, linux@....linux.org.uk, sudeep.holla@....com,
        lorenzo.pieralisi@....com, catalin.marinas@....com,
        will.deacon@....com, morten.rasmussen@....com, broonie@...nel.org,
        gregkh@...uxfoundation.org, Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH 6/7] arm, arm64: factorize common cpu capacity default
 code

On 19/01/17 14:37, Juri Lelli wrote:
> arm and arm64 share lot of code relative to parsing CPU capacity
> information from DT, using that information for appropriate scaling and
> exposing a sysfs interface for chaging such values at runtime.
> 
> Factorize such code in a common place (driver/base/arch_topology.c) in
> preparation for further additions.
> 
> Suggested-by: Will Deacon <will.deacon@....com>
> Suggested-by: Mark Rutland <mark.rutland@....com>
> Suggested-by: Catalin Marinas <catalin.marinas@....com>
> Cc: Russell King <linux@...linux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Juri Lelli <juri.lelli@....com>
> ---
>  arch/arm/Kconfig             |   1 +
>  arch/arm/kernel/topology.c   | 213 ++------------------------------------
>  arch/arm64/Kconfig           |   1 +
>  arch/arm64/kernel/topology.c | 213 +-------------------------------------
>  drivers/base/Kconfig         |   8 ++
>  drivers/base/Makefile        |   1 +
>  drivers/base/arch_topology.c | 240 +++++++++++++++++++++++++++++++++++++++++++
>  7 files changed, 260 insertions(+), 417 deletions(-)
>  create mode 100644 drivers/base/arch_topology.c

[...]

> +extern unsigned long
> +arch_scale_cpu_capacity(struct sched_domain *sd, int cpu);

How about adding a driver specific prefix 'foo_' to all driver interfaces?

I'm asking because I would rather like to do a

#define arch_scale_cpu_capacity foo_scale_cpu_capacity

then a

#define arch_scale_cpu_capacity arch_scale_cpu_capacity

in arch/arm64/include/asm/topology.h

later to wire cpu-invariant load-tracking support up to the task
scheduler for ARM64.

That's probably true too for all the 'driver' interfaces which get used
in arch/arm{,64}/kernel/topology.c.

[...]