From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [RFC PATCH 0/3] If an IRQ is a GPIO, request and configure it Date: Fri, 5 Aug 2011 22:40:27 +0100 Message-ID: <20110805214027.GA4699@n2100.arm.linux.org.uk> References: <1312498820-2275-1-git-send-email-swarren@nvidia.com> <20110805094017.GC20575@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171EFC@HQMAIL01.nvidia.com> <20110805191504.GB28958@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> Sender: linux-mmc-owner@vger.kernel.org To: Stephen Warren Cc: Thomas Gleixner , Mark Brown , Liam Girdwood , Chris Ball , "ccross@android.com" , "olof@lixom.net" , "alsa-devel@alsa-project.org" , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" List-Id: linux-tegra@vger.kernel.org On Fri, Aug 05, 2011 at 12:33:31PM -0700, Stephen Warren wrote: > Russell King - ARM Linux wrote at Friday, August 05, 2011 1:15 PM: > > On Fri, Aug 05, 2011 at 08:43:20AM -0700, Stephen Warren wrote: > > > Russell King - ARM Linux wrote at Friday, August 05, 2011 3:40 AM: > > > > On Thu, Aug 04, 2011 at 05:00:17PM -0600, Stephen Warren wrote: > > > > > In http://www.spinics.net/lists/linux-tegra/msg01731.html, Mark Brown > > > > > pointed out that it was a little silly forcing every board or driver > > > > > to gpio_request() a GPIO that is later converted to an IRQ, and passed > > > > > to request_irq. The first patch in this series instead makes the core > > > > > IRQ code perform these calls when appropriate, to avoid duplicating it > > > > > everywhere. > > > > > > > > Trying to go from IRQ to GPIO is not a good idea - most of the > > > > IRQ <-> GPIO macros we have today are just plain broken. Many of them > > > > just add or subtract a constant, which means non-GPIO IRQs have an > > > > apparant GPIO number too. Couple this with the fact that all positive > > > > GPIO numbers are valid, and this is a recipe for wrong GPIOs getting > > > > used and GPIOs being requested for non-GPIO IRQs. > > > > > > > > I think this was also discussed in the past, and the conclusion was that > > > > IRQs should be kept separate from GPIOs. Maybe views have changed since > > > > then... > > > > > > > > However, if we do want to do this, then it would be much better to provide > > > > a new API for requesting GPIO IRQs, eg: > > > > > > > > gpio_request_irq() > > > > > > > > which would wrap around request_threaded_irq(), takes a GPIO number, > > > > does the GPIO->IRQ conversion internally, and whatever GPIO setup is > > > > required. Something like this: > > > > > > With that approach, drivers need to explicitly know whether they're > > > passed a GPIO or an IRQ, and do something different, or they need to > > > choose to only accept a GPIO or IRQ. > > > > You completely missed the biggest reason why your approach is broken. > > No, I didn't. Yes you did. > I was discussing whether an alternative API for IRQ registration > would work, and I was pointing out some problems with it. > > That has nothing to do with whether my original proposal is workable. And that proves that you missed the point. I am suggesting an alternative solution precisely because your original proposal is unworkable. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756580Ab1HEVlH (ORCPT ); Fri, 5 Aug 2011 17:41:07 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:53369 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754501Ab1HEVlE (ORCPT ); Fri, 5 Aug 2011 17:41:04 -0400 Date: Fri, 5 Aug 2011 22:40:27 +0100 From: Russell King - ARM Linux To: Stephen Warren Cc: Thomas Gleixner , Mark Brown , Liam Girdwood , Chris Ball , "ccross@android.com" , "olof@lixom.net" , "alsa-devel@alsa-project.org" , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RFC PATCH 0/3] If an IRQ is a GPIO, request and configure it Message-ID: <20110805214027.GA4699@n2100.arm.linux.org.uk> References: <1312498820-2275-1-git-send-email-swarren@nvidia.com> <20110805094017.GC20575@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171EFC@HQMAIL01.nvidia.com> <20110805191504.GB28958@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 05, 2011 at 12:33:31PM -0700, Stephen Warren wrote: > Russell King - ARM Linux wrote at Friday, August 05, 2011 1:15 PM: > > On Fri, Aug 05, 2011 at 08:43:20AM -0700, Stephen Warren wrote: > > > Russell King - ARM Linux wrote at Friday, August 05, 2011 3:40 AM: > > > > On Thu, Aug 04, 2011 at 05:00:17PM -0600, Stephen Warren wrote: > > > > > In http://www.spinics.net/lists/linux-tegra/msg01731.html, Mark Brown > > > > > pointed out that it was a little silly forcing every board or driver > > > > > to gpio_request() a GPIO that is later converted to an IRQ, and passed > > > > > to request_irq. The first patch in this series instead makes the core > > > > > IRQ code perform these calls when appropriate, to avoid duplicating it > > > > > everywhere. > > > > > > > > Trying to go from IRQ to GPIO is not a good idea - most of the > > > > IRQ <-> GPIO macros we have today are just plain broken. Many of them > > > > just add or subtract a constant, which means non-GPIO IRQs have an > > > > apparant GPIO number too. Couple this with the fact that all positive > > > > GPIO numbers are valid, and this is a recipe for wrong GPIOs getting > > > > used and GPIOs being requested for non-GPIO IRQs. > > > > > > > > I think this was also discussed in the past, and the conclusion was that > > > > IRQs should be kept separate from GPIOs. Maybe views have changed since > > > > then... > > > > > > > > However, if we do want to do this, then it would be much better to provide > > > > a new API for requesting GPIO IRQs, eg: > > > > > > > > gpio_request_irq() > > > > > > > > which would wrap around request_threaded_irq(), takes a GPIO number, > > > > does the GPIO->IRQ conversion internally, and whatever GPIO setup is > > > > required. Something like this: > > > > > > With that approach, drivers need to explicitly know whether they're > > > passed a GPIO or an IRQ, and do something different, or they need to > > > choose to only accept a GPIO or IRQ. > > > > You completely missed the biggest reason why your approach is broken. > > No, I didn't. Yes you did. > I was discussing whether an alternative API for IRQ registration > would work, and I was pointing out some problems with it. > > That has nothing to do with whether my original proposal is workable. And that proves that you missed the point. I am suggesting an alternative solution precisely because your original proposal is unworkable. From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Fri, 5 Aug 2011 22:40:27 +0100 Subject: [RFC PATCH 0/3] If an IRQ is a GPIO, request and configure it In-Reply-To: <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> References: <1312498820-2275-1-git-send-email-swarren@nvidia.com> <20110805094017.GC20575@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171EFC@HQMAIL01.nvidia.com> <20110805191504.GB28958@n2100.arm.linux.org.uk> <74CDBE0F657A3D45AFBB94109FB122FF049F171FD3@HQMAIL01.nvidia.com> Message-ID: <20110805214027.GA4699@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Aug 05, 2011 at 12:33:31PM -0700, Stephen Warren wrote: > Russell King - ARM Linux wrote at Friday, August 05, 2011 1:15 PM: > > On Fri, Aug 05, 2011 at 08:43:20AM -0700, Stephen Warren wrote: > > > Russell King - ARM Linux wrote at Friday, August 05, 2011 3:40 AM: > > > > On Thu, Aug 04, 2011 at 05:00:17PM -0600, Stephen Warren wrote: > > > > > In http://www.spinics.net/lists/linux-tegra/msg01731.html, Mark Brown > > > > > pointed out that it was a little silly forcing every board or driver > > > > > to gpio_request() a GPIO that is later converted to an IRQ, and passed > > > > > to request_irq. The first patch in this series instead makes the core > > > > > IRQ code perform these calls when appropriate, to avoid duplicating it > > > > > everywhere. > > > > > > > > Trying to go from IRQ to GPIO is not a good idea - most of the > > > > IRQ <-> GPIO macros we have today are just plain broken. Many of them > > > > just add or subtract a constant, which means non-GPIO IRQs have an > > > > apparant GPIO number too. Couple this with the fact that all positive > > > > GPIO numbers are valid, and this is a recipe for wrong GPIOs getting > > > > used and GPIOs being requested for non-GPIO IRQs. > > > > > > > > I think this was also discussed in the past, and the conclusion was that > > > > IRQs should be kept separate from GPIOs. Maybe views have changed since > > > > then... > > > > > > > > However, if we do want to do this, then it would be much better to provide > > > > a new API for requesting GPIO IRQs, eg: > > > > > > > > gpio_request_irq() > > > > > > > > which would wrap around request_threaded_irq(), takes a GPIO number, > > > > does the GPIO->IRQ conversion internally, and whatever GPIO setup is > > > > required. Something like this: > > > > > > With that approach, drivers need to explicitly know whether they're > > > passed a GPIO or an IRQ, and do something different, or they need to > > > choose to only accept a GPIO or IRQ. > > > > You completely missed the biggest reason why your approach is broken. > > No, I didn't. Yes you did. > I was discussing whether an alternative API for IRQ registration > would work, and I was pointing out some problems with it. > > That has nothing to do with whether my original proposal is workable. And that proves that you missed the point. I am suggesting an alternative solution precisely because your original proposal is unworkable.