linux-kernel - Re: [PATCH] regulator: Rename files for Maxim PMIC drivers

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Message-id: <56EB762D.9070200@samsung.com>
Date:	Fri, 18 Mar 2016 12:29:49 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Javier Martinez Canillas <javier@....samsung.com>,
	linux-kernel@...r.kernel.org
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH] regulator: Rename files for Maxim PMIC drivers

On 18.03.2016 11:41, Javier Martinez Canillas wrote:
> Hello Krzysztof,
> 
> Thanks a lot for your review.
> 
> On 03/17/2016 09:07 PM, Krzysztof Kozlowski wrote:
>> On 18.03.2016 02:54, Javier Martinez Canillas wrote:
>>> Most Maxim PMIC regulator drivers are for sub-devices of Multi-Function
>>> Devices with drivers under drivers/mfd. But for many of these, the same
>>> object file name was used for both the MFD and the regulator drivers.
>>>
>>> Having 2 different drivers with the same name causes a lot of confusion
>>> to Kbuild, specially if these are built as module since only one module
>>> will be installed and also exported symbols will be undefined due being
>>> overwritten by the other module during modpost.
>>
>> These regulator drivers do not export symbols. In case of max14577 only
>> main MFD driver exports symbols so what do you mean by "overwriting by
>> other module"?
>>
> 
> That's correct, what I meant is that if only the MFD driver is built, then
> Kbuild / modpost are able to obtain the exported symbols and add it to the
> Module.symvers file.
> 
> But if the regulator driver is also built, then the build system isn't able
> to handle that case and the exported symbols from Module.symvers disappear.
> 
> So IIUC what happens is that the build system gets the exported symbols from
> the max14755 MFD module but then finds another module that has the same name
> (with no exported symbols) and so discards the list of symbols that previously
> had for that module. That's why I used the "overwriting by the other module".

Ah, that indeed makes sense. Thanks for careful explanation.

Best regards,
Krzysztof