linux-kernel - Re: [PATCH] pwm-backlight: Pinctrl-fy

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Date:	Sun, 11 Nov 2012 19:26:38 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Thierry Reding <thierry.reding@...onic-design.de>
Cc:	Pantelis Antoniou <panto@...oniou-consulting.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Florian Tobias Schandinat <FlorianSchandinat@....de>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Koen Kooi <koen@...inion.thruhere.net>,
	Matt Porter <mporter@...com>, Russ Dill <Russ.Dill@...com>,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH] pwm-backlight: Pinctrl-fy

On Fri, Nov 9, 2012 at 9:06 AM, Thierry Reding
<thierry.reding@...onic-design.de> wrote:
> On Wed, Oct 31, 2012 at 05:57:27PM +0200, Pantelis Antoniou wrote:

>> +     pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
>> +     if (IS_ERR(pinctrl))
>> +             dev_warn(&pdev->dev, "unable to select pin group\n");
>> +
>
> I just saw this done in a similar way in some other driver and then
> remembered your patch. When I reviewed this I wasn't sure if a warning
> was good enough in this case. I've checked the kernel tree and it seems
> like a majority handled this as failure instead of a warning. I took a
> look at the pinctrl core and it seems like indeed if neither pinctrl is
> enabled or if there isn't actually a pinmux configuration for a device,
> then devm_pinctrl_get_select_default() will actually not return an
> error, so in those cases where an error is returned it should actually
> be handled as a fatal error.

So it depends.

One good reason to just error out and return the error code is
if the error returned is -EPROBE_DEFER, right?

Because then you're pinctrl driver is not up yet, and you
need to bail out and be revisited later.

On a related key we have this debate going on with some
subsystem maintainers as to whether we should try do
centralize boilerplate like this, the lates suggestion is:
http://marc.info/?l=linux-kernel&m=135263661110528&w=2

The fun never ends...

Yours,
Linus Walleij
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