Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752179Ab3IJTxy (ORCPT ); Tue, 10 Sep 2013 15:53:54 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:55872 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751359Ab3IJTxw (ORCPT ); Tue, 10 Sep 2013 15:53:52 -0400 Message-ID: <522F78CB.2020507@wwwdotorg.org> Date: Tue, 10 Sep 2013 13:53:47 -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: Lars Poeschel CC: Mark Brown , Javier Martinez Canillas , Linus Walleij , Lars Poeschel , Grant Likely , "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Mark Rutland , Ian Campbell , Kumar Gala , Pawel Moll , Tomasz Figa , Enric Balletbo i Serra , Jean-Christophe PLAGNIOL-VILLARD , Santosh Shilimkar , Kevin Hilman , Balaji T K , Tony Lindgren , Jon Hunter Subject: Re: [PATCH v3] gpio: interrupt consistency check for OF GPIO IRQs References: <1377526030-32024-1-git-send-email-larsi@wh2.tu-dresden.de> <52279524.8090006@wwwdotorg.org> <20130909161924.GT29403@sirena.org.uk> <2052193.CMUEUJFRgS@lem-wkst-02> In-Reply-To: <2052193.CMUEUJFRgS@lem-wkst-02> 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: 1797 Lines: 34 On 09/10/2013 02:47 AM, Lars Poeschel wrote: > On Tuesday 10 September 2013 17:19:24, Mark Brown wrote: >> On Wed, Sep 04, 2013 at 02:16:36PM -0600, Stephen Warren wrote: >>> On 09/04/2013 03:05 AM, Lars Poeschel wrote: >>>> The driver that tries to use the GPIO requested by this patch before HAS >>>> to >>>> fail. This is exactly the intention of this patch. We don't want the >>>> GPIO to be requested any more, if it is used as an interrupt pin. >>> >>> That will break existing drivers. There are drivers that request the >>> same GPIO and IRQ. IIRC, the SDHCI CD (Card Detect) GPIO is requested >>> that way. >> >> Yes, plus input devices and audio jack detection among others. This >> pattern is very common if the GPIO is actually being used as a GPIO, an >> edge triggered interrupt is used to flag when something happens and the >> state is determined by reading the GPIO state (often with some >> debounce). > > And I say it again for those coming into the discussion late, like it has been > said many many times before: This patch does not break any of this drivers. > They simply request their GPIO from DT and turn it into an irq using > gpio_to_irq, request that irq on their behalf and use it as GPIO and IRQ in > parallel. At least this is not a problem. Doesn't this patch call gpio_request() on the GPIO first, and hence prevent the driver's own gpio_request() from succeeding, since the GPIO is already requested? If this is not a problem, it sounds like a bug in gpio_request() not ensuring mutual exclusion for the GPIO. -- 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/