linux-kernel - Re: [PATCH] platform/chrome: Make CROS_EC

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Date:	Tue, 18 Aug 2015 15:36:13 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	Olof Johansson <olof@...om.net>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Doug Anderson <dianders@...omium.org>,
	Gwendal Grignou <gwendal@...omium.org>,
	Sjoerd Simons <sjoerd.simons@...labora.co.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/chrome: Make CROS_EC_PROTO a user selectable
 option


Hi,

On Tuesday, August 18, 2015 03:02:26 PM Javier Martinez Canillas wrote:
> Hello Bartlomiej,
> 
> Thanks a lot for your feedback.
> 
> On 08/18/2015 02:40 PM, Bartlomiej Zolnierkiewicz wrote:
> > 
> > Hi,
> > 
> > On Tuesday, August 18, 2015 09:15:06 AM Javier Martinez Canillas wrote:
> >> The boolean CROS_EC_PROTO symbol is selected by MFD_CROS_EC but that can
> >> cause Kconfig circular dependencies so is better to change the select to
> > 
> > Could you please give a reference to the problem or error message
> > that you're getting (I was not following the previous discussion).
> >
> 
> Yes, the original Kconfig warning message was:
> 
> warning: (MFD_CROS_EC) selects CHROME_PLATFORMS which has unmet direct dependencies (X86 || ARM)
> 
> Paul fixed on [0] by making MFD_CROS_EC depends on X86 || ARM but that
> is not really true since the driver could be used in other platforms so
> I tried to instead fix it by removing unneeded dependencies in [1] but
> one of the patches was nacked by Geert [2] who mentioned the issue about
> mixing select and "depends on".

I think that Geert's comments are valid.  Dependencies should limit
the config option to the archs for which the driver is really needed
(the rest can be handled with COMPILE_TEST dependency).

> >> a depends on. But in order to be able to change that, the CROS_EC_PROTO
> >> symbol has to be one that can be selected by the user.
> > 
> > Looking at the code behind the config option it seems that it is just
> > a helper library and should not be made user-visible.  Why can't
> 
> Yeah, I in fact used as a reference the DRM/KMS helpers (DRM_KMS_HELPER)
> that is selected by drivers instead of depending on it.
> 
> > the issue be fixed the other way (make other config options select
> > CROS_EC_PROTO consistently)?
> >
> 
> That is another option indeed. I thought that the use of select was
> discouraged and that it was preferable to use "depends on" even when
> the Kconfig symbol is a boolean to enable support for some helpers.

No, this is not true.  It is just that "select" has to be used with
care. ;)

> But I don't really have a strong opinion on either approach tbh.

Please rework your patches to use "select".

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
 
> > Best regards,
> > --
> > Bartlomiej Zolnierkiewicz
> > Samsung R&D Institute Poland
> > Samsung Electronics
> > 
> 
> [0]: https://lkml.org/lkml/2015/6/20/219
> [1]: https://lkml.org/lkml/2015/6/24/689
> [2]: https://lkml.org/lkml/2015/8/17/103
> 
> Best regards,

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