linux-kernel - Re: [PATCH 6/6] cpufreq: pxa: convert to clock API

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Date:   Wed, 12 Oct 2016 21:12:26 +0200
From:   Robert Jarzmik <robert.jarzmik@...e.fr>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 6/6] cpufreq: pxa: convert to clock API

Viresh Kumar <viresh.kumar@...aro.org> writes:

>> >> PXA architecture have both legacy platform_data based configurations and new
>> >> devicetree based ones.
>> >
>> > I don't see any platform data specific code in this driver. What am I
>> > missing ?
>> 
>> In a legacy platform, ie. without devicetree, we have CONFIG_OF=n.
>> How would cpufreq-dt be usable in this case ?
>> 
>> You can see such a platform in arch/arm/configs/mainstone_defconfig and
>> arch/arm/mach-pxa/mainstone.c as an example.
>
> Okay, so its not about platform_data as you said earlier. Rather it is
> about the CONFIG_OF option.
We're bickering about terminology.

Mine is that there are globally :
 - platform_data _based_  configurations
   => drivers probing devices rely on platform_data structures for initial
   configuration
   => that implies CONFIG_OF=n
   => pxa2xx-cpufreq is one of them, even if in this case no platform_data is
   used
   
 - devicetree based configurations
   => drivers probing devices rely on device-tree blob for initial configuration
   => that implies CONFIG_OF=y

 - ACPI based configurations
   => drivers probing devices rely on ACPI data

 - maybe PCI would deserve a place, but I don't think there is much
   configuration in it

> In that case, what about making this driver depends_on !CONFIG_OF ? So
> that the DT users don't use it anymore.
Good idea, let me try it.
I'll see if it actually works before make another iteration of this patch.

Cheers.

-- 
Robert