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From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Stephen Warren <swarren@nvidia.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Liam Girdwood <lrg@ti.com>,
	Chris Ball <cjb@laptop.org>,
	"ccross@android.com" <ccross@android.com>,
	"olof@lixom.net" <olof@lixom.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it
Date: Fri, 5 Aug 2011 06:35:11 +0100	[thread overview]
Message-ID: <20110805053510.GA16956@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF049F171EC1@HQMAIL01.nvidia.com>

On Thu, Aug 04, 2011 at 08:53:34PM -0700, Stephen Warren wrote:

> Well, things break. This is essentially the problem I was describing in
> the PATCH 0 email, just with a slightly different motivation.

There's a bunch of existing code using that idiom.

> I suppose that an alternative here would be to simply ignore any errors
> from gpio_request. This might have the benefit of removing the need for
> the other two patches I posted in the series. However, it seems a little
> dirty; one benefit of the IRQ code calling gpio_request and honoring
> errors would be to detect when some completely unrelated code had a bug
> and had called gpio_request on the GPIO before. Such detection would be
> non-existent if we don't error out on gpio_request. Perhaps some mechanism
> is needed to indicate that the driver has explicitly already called
> gpio_request for a legitimate shared purpose, and only then ignore
> errors?

But it's not a bug to use a GPIO as an IRQ source, otherwise we wouldn't
have gpio_to_irq() in the first place.  Feels like we need a backchannel
between gpiolib and the IRQ code to do this.  Or perhaps the drivers
that implement this should be taking care of setting up the GPIO mode?

WARNING: multiple messages have this Message-ID (diff)
From: broonie@opensource.wolfsonmicro.com (Mark Brown)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/3] irq: If an IRQ is a GPIO, request and configure it
Date: Fri, 5 Aug 2011 06:35:11 +0100	[thread overview]
Message-ID: <20110805053510.GA16956@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF049F171EC1@HQMAIL01.nvidia.com>

On Thu, Aug 04, 2011 at 08:53:34PM -0700, Stephen Warren wrote:

> Well, things break. This is essentially the problem I was describing in
> the PATCH 0 email, just with a slightly different motivation.

There's a bunch of existing code using that idiom.

> I suppose that an alternative here would be to simply ignore any errors
> from gpio_request. This might have the benefit of removing the need for
> the other two patches I posted in the series. However, it seems a little
> dirty; one benefit of the IRQ code calling gpio_request and honoring
> errors would be to detect when some completely unrelated code had a bug
> and had called gpio_request on the GPIO before. Such detection would be
> non-existent if we don't error out on gpio_request. Perhaps some mechanism
> is needed to indicate that the driver has explicitly already called
> gpio_request for a legitimate shared purpose, and only then ignore
> errors?

But it's not a bug to use a GPIO as an IRQ source, otherwise we wouldn't
have gpio_to_irq() in the first place.  Feels like we need a backchannel
between gpiolib and the IRQ code to do this.  Or perhaps the drivers
that implement this should be taking care of setting up the GPIO mode?

  reply	other threads:[~2011-08-05  5:35 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-04 23:00 [RFC PATCH 0/3] If an IRQ is a GPIO, request and configure it Stephen Warren
2011-08-04 23:00 ` Stephen Warren
2011-08-04 23:00 ` Stephen Warren
     [not found] ` <1312498820-2275-1-git-send-email-swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2011-08-04 23:00   ` [PATCH 1/3] irq: " Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-05  0:01     ` Mark Brown
2011-08-05  0:01       ` Mark Brown
2011-08-05  0:01       ` Mark Brown
     [not found]       ` <20110805000148.GB13321-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2011-08-05  3:53         ` Stephen Warren
2011-08-05  3:53           ` Stephen Warren
2011-08-05  3:53           ` Stephen Warren
2011-08-05  5:35           ` Mark Brown [this message]
2011-08-05  5:35             ` Mark Brown
2011-08-05  5:35             ` Mark Brown
     [not found]             ` <20110805053510.GA16956-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2011-08-05  8:06               ` Ben Dooks
2011-08-05  8:06                 ` Ben Dooks
2011-08-05  8:06                 ` Ben Dooks
2011-08-05  8:29                 ` Mark Brown
2011-08-05  8:29                   ` Mark Brown
2011-08-05  8:29                   ` Mark Brown
2011-08-05 15:29             ` Stephen Warren
2011-08-05 15:29               ` Stephen Warren
2011-08-05 15:29               ` Stephen Warren
2011-08-05 16:15               ` Mark Brown
2011-08-05 16:15                 ` Mark Brown
2011-08-05 16:15                 ` Mark Brown
2011-08-05  1:54     ` Rob Herring
2011-08-05  1:54       ` Rob Herring
2011-08-05  4:05       ` Stephen Warren
2011-08-05  4:05         ` Stephen Warren
2011-08-05  4:05         ` Stephen Warren
2011-08-05  7:58     ` Ben Dooks
2011-08-05  7:58       ` Ben Dooks
2011-09-02  8:36     ` Thomas Gleixner
2011-09-02  8:36       ` Thomas Gleixner
2011-09-02 15:24       ` Stephen Warren
2011-09-02 15:24         ` Stephen Warren
2011-09-02 15:24         ` Stephen Warren
     [not found]         ` <74CDBE0F657A3D45AFBB94109FB122FF04B327A55C-C7FfzLzN0UxDw2glCA4ptUEOCMrvLtNR@public.gmane.org>
2011-09-02 15:34           ` Stephen Warren
2011-09-02 15:34             ` Stephen Warren
2011-09-02 15:34             ` Stephen Warren
2011-09-02 15:50           ` Thomas Gleixner
2011-09-02 15:50             ` Thomas Gleixner
2011-09-02 15:50             ` Thomas Gleixner
2011-08-04 23:00   ` [PATCH 2/3] mmc: tegra: Don't gpio_request GPIOs used as IRQs Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-04 23:00   ` [PATCH 3/3] ASoC: jack_add_gpios: " Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-04 23:00     ` Stephen Warren
2011-08-05  7:55   ` [RFC PATCH 0/3] If an IRQ is a GPIO, request and configure it Ben Dooks
2011-08-05  7:55     ` Ben Dooks
2011-08-05  7:55     ` Ben Dooks
2011-08-05  9:40 ` Russell King - ARM Linux
2011-08-05  9:40   ` Russell King - ARM Linux
     [not found]   ` <20110805094017.GC20575-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2011-08-05 10:30     ` Ben Dooks
2011-08-05 10:30       ` Ben Dooks
2011-08-05 10:30       ` Ben Dooks
2011-08-05 20:25       ` Linus Walleij
2011-08-05 20:25         ` Linus Walleij
2011-08-05 15:43   ` Stephen Warren
2011-08-05 15:43     ` Stephen Warren
2011-08-05 15:43     ` Stephen Warren
2011-08-05 19:15     ` Russell King - ARM Linux
2011-08-05 19:15       ` Russell King - ARM Linux
2011-08-05 19:15       ` Russell King - ARM Linux
2011-08-05 19:33       ` Stephen Warren
2011-08-05 19:33         ` Stephen Warren
2011-08-05 19:33         ` Stephen Warren
2011-08-05 21:40         ` Russell King - ARM Linux
2011-08-05 21:40           ` Russell King - ARM Linux
2011-08-05 21:40           ` Russell King - ARM Linux

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