linux-kernel - Re: [PATCH 1/3] firmware: of: populate /firmware/ node during init

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Message-ID: <01aa3488-944e-b98c-65a4-7ec1b31af208@arm.com>
Date:   Fri, 11 Aug 2017 16:37:15 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        Rob Herring <robh@...nel.org>,
        Andy Gross <andy.gross@...aro.org>,
        Jens Wiklander <jens.wiklander@...aro.org>
Subject: Re: [PATCH 1/3] firmware: of: populate /firmware/ node during init



On 11/08/17 15:37, Arnd Bergmann wrote:
> On Fri, Aug 11, 2017 at 3:30 PM, Sudeep Holla <sudeep.holla@....com> wrote:
>> Since "/firmware" does not have its own "compatible" property as it's
>> just collection of nodes representing firmware interface, it's sub-nodes
>> are not populated during system initialization.
>>
>> Currently different firmware drivers search the /firmware/ node and
>> populate the sub-node devices selectively. Instead we can populate
>> the /firmware/ node during init to avoid more drivers continuing to
>> populate the devices selectively.
>>
>> This patch adds initcall to achieve the same.
> 
> Hmm, I'm a bit skeptical whether representing anything under /firmware
> as a platform device is a good idea. Having a more structured way to
> probe those seems like a good idea, but maybe a different subsystem
> would be more appropriate.
> 

Just a vague thought: if we go to an extent of creating a bus to deal
with these, won't we need to be more formal and create compatible for that ?

If we do that, then how do we support existing device trees ? Again we
are back to the same point but I do agree with your views.

> I do realize that a 'platform_device' has become a rather generic abstraction
> for almost anything, but at some point we might want to draw the line
> of what is a platform_device.
> 

As Rob pointed out it's already being handled as platform_devices in
many cases and my aim was just to reduce the duplication.

-- 
Regards,
Sudeep