linux-kernel - Re: [PATCH] regulator: fixed: support deferred probe for DT GPIOs

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Message-ID: <20120630114857.GW28922@opensource.wolfsonmicro.com>
Date:	Sat, 30 Jun 2012 12:48:58 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Liam Girdwood <lrg@...com>, linux-kernel@...r.kernel.org,
	Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH] regulator: fixed: support deferred probe for DT GPIOs

On Fri, Jun 29, 2012 at 09:30:51AM -0600, Stephen Warren wrote:

> I did consider making of_get_fixed_voltage_config() return a result
> code, but then it needs some other way of returning the pointer, so
> that seemed just as convoluted. Oh, I suppose it could use ERR_PTR()
> to do that; that'd be nice and simple. Would that do?

Meh, or just have the caller pass in the platform data rather than
allocate it in the function.

> Re: gpiolib doing it: How is that possible? of_get_named_gpio()
> certainly can return -EPROBE_DEFER, but the caller would still need to
> check it. The ideal case might be to just do:

> ret = gpio_request(of_get_named_gpio(...));
> if (ret)
>     return ret;

> and have gpio_request pass -EPROBE_DEFER from input to output.

Even better just have gpio_request() just return -EPROBE_DEFER instead
of -ENODEV.  There is no sane case where you'd request a GPIO you didn't
have a reasonable idea was going to be registered at some point (or
could be with appropriate system configuration) so we should just assume
that might happen.

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