linux-kernel - Re: [PATCH v2 1/4] cpufreq: pxa: use generic platdev driver for device-tree

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Message-ID: <87bmyg3xzh.fsf@belgarion.home>
Date:   Wed, 19 Oct 2016 22:06:10 +0200
From:   Robert Jarzmik <robert.jarzmik@...e.fr>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 1/4] cpufreq: pxa: use generic platdev driver for device-tree

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

>> >> +	{ .compatible = "marvell,pxa250", },
>> >> +	{ .compatible = "marvell,pxa270", },
>> >>  
>> >>  	{ .compatible = "samsung,exynos3250", },
>> >>  	{ .compatible = "samsung,exynos4210", },
>> >
>> > Isn't there a race between cpufreq-dt and the platform driver to
>> > register first ?
>> Ah, could you be more specific about the race you're talking of ?
>> 
>> My understanding was that cpufreq-dt-platdev does create the device, and
>> cpufreq-dt is a driver for it, so there is no race but a direct relationship
>> AFAIU.
>
> I mean that both the driver may try to register to the cpufreq core if
> they are both compiled in a single image.
Euh I still don't follow you. The only driver that can register to the cpufreq
core is cpufreq-dt.

Now the only case I see is that there are 2 cpufreq-dt platform_device created
from cpufreq-dt-platdev. Given that there is only 1 call to
platform_device_register_data() in it, I don't see how it is possible.

Now if you are worried that 2 cpufreq-dt devices are created, ie. 1 for pxa25x
and one for pxa27x:
 - this looks impossible given the cpufreq_dt_platdev_init() code
 - no device-tree will ever be compatible with both of them, even if a single
   kernel binary will be compatible with both of them

Tell me if this is the information you're looking for.

Cheers.

-- 
Robert