linux-kernel - Re: [PATCH 2/2] gpio: of: Allow -gpio suffix for property names

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Date:	Wed, 4 Jun 2014 15:08:39 +0200
From:	Thierry Reding <thierry.reding@...il.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH 2/2] gpio: of: Allow -gpio suffix for property names

On Mon, Jun 02, 2014 at 04:14:23PM -0700, Tony Lindgren wrote:
> * Tony Lindgren <tony@...mide.com> [140602 16:06]:
> > * Linus Walleij <linus.walleij@...aro.org> [140425 00:53]:
> > > On Wed, Apr 23, 2014 at 5:28 PM, Thierry Reding
> > > <thierry.reding@...il.com> wrote:
> > > 
> > > > From: Thierry Reding <treding@...dia.com>
> > > >
> > > > Many bindings use the -gpio suffix in property names. Support this in
> > > > addition to the -gpios suffix when requesting GPIOs using the new
> > > > descriptor-based API.
> > > >
> > > > Signed-off-by: Thierry Reding <treding@...dia.com>
> > > 
> > > It appears this can save quite a lot of code in drivers, work that
> > > I trust Thierry to persue based on this to some extent so patch is
> > > tentatively applied unless something comes up.
> > 
> > Looks like this patch causes a regression where GPIOs on I2C will
> > no longer return -EPROBE_DEFER but seem to return -ENOENT instead.
> > 
> > This breaks drivers using things like devm_gpiod_get_index()
> > on a GPIO that's on a I2C bus not probed yet.
> > 
> > Reverting commit dd34c37aa3e (gpio: of: Allow -gpio suffix for
> > property names) fixes things.
> 
> Looks like something like below fixes the issue.
> 
> Regards,
> 
> Tony
> 
> 8< -----------------------
> From: Tony Lindgren <tony@...mide.com>
> Date: Mon, 2 Jun 2014 16:13:46 -0700
> Subject: [PATCH] gpio: of: Fix handling for deferred probe for -gpio suffix
> 
> Commit dd34c37aa3e (gpio: of: Allow -gpio suffix for property names)
> added parsing for both -gpio and -gpios suffix but also changed
> the handling for deferred probe unintentionally. Because of the
> looping the second name will now return -ENOENT instead of
> -EPROBE_DEFER. Fix the issue by breaking out of the loop if
> -EPROBE_DEFER is encountered.
> 
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> 
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2614,7 +2614,7 @@ static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
>  
>  		desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
>  						&of_flags);
> -		if (!IS_ERR(desc))
> +		if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))
>  			break;
>  	}

This looks good to me:

Reviewed-by: Thierry Reding <treding@...dia.com>

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