Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754369Ab3HVVLA (ORCPT ); Thu, 22 Aug 2013 17:11:00 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:60267 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753049Ab3HVVK6 (ORCPT ); Thu, 22 Aug 2013 17:10:58 -0400 Message-ID: <52167E5D.6060802@wwwdotorg.org> Date: Thu, 22 Aug 2013 15:10:53 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Linus Walleij CC: Tomasz Figa , Lars Poeschel , Lars Poeschel , Grant Likely , "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Mark Rutland , Ian Campbell , galak@codeaurora.org, Pawel Moll , Javier Martinez Canillas , Enric Balletbo i Serra , Jean-Christophe PLAGNIOL-VILLARD , Santosh Shilimkar , Kevin Hilman , Balaji T K , Tony Lindgren , Jon Hunter Subject: Re: [PATCH v2] gpio: interrupt consistency check for OF GPIO IRQs References: <1377092334-770-1-git-send-email-larsi@wh2.tu-dresden.de> <1507189.CRWvzVJqTV@flatron> <521548E3.6010703@wwwdotorg.org> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1352 Lines: 27 On 08/21/2013 05:36 PM, Linus Walleij wrote: > On Thu, Aug 22, 2013 at 1:10 AM, Stephen Warren wrote: > [Me] >>>> check if these in turn reference the interrupt-controller, and >>>> if they do, loop over the interrupts used by that child and >>>> perform gpio_request() and gpio_direction_input() on these, >>>> making them unreachable from the GPIO side. >> >> What about bindings that require a GPIO to be specified, yet don't allow >> an IRQ to be specified, and the driver internally does perform >> gpio_to_irq() on it? I don't think one can detect that case. > > This is still allowed. Consumers that prefer to have a GPIO > passed and convert it to IRQ by that call can still do so, > they will know what they're doing and will not cause the > double-command situation that we're trying to solve. Why not? There are certainly drivers in the kernel which request a GPIO as both a GPIO and as an (dual-edge) interrupt, so that they can read the GPIO input whenever the IRQ goes off, in order to determine the pin state. This is safer against high-latency or lost interrupts. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/