linux-kernel - Re: [PATCH V2 3/3] pinctrl: Add Pistachio SoC pin control driver

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Message-ID: <CACRpkdYfN_AV47G8cni=gApcwf8nx_fUrreGZp7ASRsU5PM1bA@mail.gmail.com>
Date:	Tue, 7 Apr 2015 16:13:16 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Andrew Bresticker <abrestic@...omium.org>
Cc:	Paul Bolle <pebolle@...cali.nl>,
	Alexandre Courbot <gnurou@...il.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux-MIPS <linux-mips@...ux-mips.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ezequiel Garcia <ezequiel.garcia@...tec.com>,
	James Hartley <james.hartley@...tec.com>,
	James Hogan <james.hogan@...tec.com>,
	Damien Horsley <Damien.Horsley@...tec.com>,
	Govindraj Raja <govindraj.raja@...tec.com>,
	Kevin Cernekee <cernekee@...omium.org>
Subject: Re: [PATCH V2 3/3] pinctrl: Add Pistachio SoC pin control driver

On Tue, Mar 31, 2015 at 6:56 PM, Andrew Bresticker
<abrestic@...omium.org> wrote:
> Hi Paul,
>
> On Tue, Mar 31, 2015 at 1:10 AM, Paul Bolle <pebolle@...cali.nl> wrote:
>> The patch adds a mismatch between the Kconfig symbol (a bool) and the
>> code (which suggests that a modular build is also possible).
>
> Nearly all of the pinctrl drivers (with the exception of qcom and
> intel) are like this.  They use a bool Kconfig symbol but they are
> written so that they could be built as a module in the future.

There are many aspects to this and I have no strong opinion,
it doesn't really disturb me either way as both are familiar
ways of writing drivers be it modular or not.

I think it's more disturbing that bool drivers have .remove()
functions, and as pointed out elsewhere this is because the
module can still be bound/unbound from sysfs even if compiled
into the kernel and then that code path will actually be executed.

And as I remarked again, elsewhere, that can be overcome
by adding the .suppress_bind_attrs = true to struct device_driver
inside the platform driver.

So if going through all the hazzle to remove anything compiled-out
for non-modules, also take the step above removing .remove()
calls and setting .suppress_bind_attrs.

I will maybe do so sometime myself for any bool drivers...

Yours,
Linus Walleij
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