linux-kernel - Re: [PATCH] gpio / ACPI: Return -EPROBE

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Message-ID: <20150611001129.GB21213@yumi.tdiedrich.de>
Date:	Thu, 11 Jun 2015 02:11:29 +0200
From:	Tobias Diedrich <ranma+kernel@...edrich.de>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio / ACPI: Return -EPROBE_DEFER if the gpiochip was
 not found

Rafael J. Wysocki wrote:
> On Wednesday, June 10, 2015 04:05:05 PM Mika Westerberg wrote:
> > If a driver requests a GPIO described in its _CRS but the GPIO host
> > controller (gpiochip) driver providing the GPIO has not been loaded yet
> > acpi_get_gpiod() returns -ENODEV which causes the calling driver to fail.
> > 
> > If the gpiochip driver is loaded afterwards the driver requesting the GPIO
> > will not notice this.
> > 
> > Better approach is to return -EPROBE_DEFER in such case. Then when the
> > gpiochip driver appears the driver requesting the GPIO will be probed
> > again. This also aligns ACPI GPIO lookup code closer to DT as it does
> > pretty much the same when no gpiochip driver was found.
> > 
> > Reported-by: Tobias Diedrich <tobiasdiedrich@...il.com>
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 
> Makes sense to me.
> 
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Signed-off-by: Tobias Diedrich <ranma+kernel@...edrich.de>

-- 
Tobias						PGP: http://8ef7ddba.uguu.de
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