linux-kernel - Re: [PATCH v2 00/22] mfd: demodularization of non-modular drivers

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Date:   Wed, 5 Dec 2018 12:48:47 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     Paul Gortmaker <paul.gortmaker@...driver.com>,
        Lee Jones <lee.jones@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Cory Maccarrone <darkstar6262@...il.com>,
        David Dajun Chen <dchen@...semi.com>,
        Dong Aisheng <dong.aisheng@...aro.org>,
        Eric Miao <eric.miao@...vell.com>,
        Graeme Gregory <gg@...mlogic.co.uk>,
        Guennadi Liakhovetski <g.liakhovetski@....de>,
        Haojian Zhuang <haojian.zhuang@...vell.com>,
        jinyoungp@...dia.com,
        Jorge Eduardo Candelaria <jedu@...mlogic.co.uk>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Mark Brown <broonie@...nsource.wolfsonmicro.com>,
        Mattias NILSSON <mattias.i.nilsson@...ricsson.com>,
        Michael Hennerich <michael.hennerich@...log.com>,
        Mike Rapoport <mike@...pulab.co.il>,
        ext Tony Lindgren <tony@...mide.com>,
        Venu Byravarasu <vbyravarasu@...dia.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        patches@...nsource.cirrus.com,
        Support Opensource <support.opensource@...semi.com>
Subject: Re: [PATCH v2 00/22] mfd: demodularization of non-modular drivers

On Wed, Dec 5, 2018 at 12:36 PM Charles Keepax
<ckeepax@...nsource.cirrus.com> wrote:
> On Sun, Dec 02, 2018 at 11:23:07PM -0500, Paul Gortmaker wrote:
> > The solution to #4 is similar - we delete the ".remove" function and
> > the binding into the platform_driver struct.  However, since the same
> > ".remove" function could also be triggered by an "unbind" (such as for
> > pass-through of a device to a guest instance)  - so we also explicitly
> > disable any unbind for the driver.
> >
> > The unbind mask allows us to ensure we will see if there was some odd
> > corner case out there that was relying on it.  Typically it would be a
> > multi-port ethernet card passing a port through to a guest, so a
> > sensible use case in MFD drivers seems highly unlikely.  This same
> > solution has already been used in multiple other mainline subsystems.
> >
>
> I guess if this is a general direction thing, but it does seem
> that module unload is not the only reason one might ever unbind a
> driver. So are we sure we want to remove the option to unbind
> these drivers? Certainly for testing it is sometimes useful.

I personally never understood why these attributes are even
present on non-modular drivers.

If testing is about exercising unbind/bind to reintialize
the code through a new call to .probe(), why would the developer
not take it all the way through and make it a module?
It just looks like a half-measure.

Yours,
Linus Walleij