Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751235Ab3IXIsN (ORCPT ); Tue, 24 Sep 2013 04:48:13 -0400 Received: from bear.ext.ti.com ([192.94.94.41]:37302 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735Ab3IXIsJ (ORCPT ); Tue, 24 Sep 2013 04:48:09 -0400 Message-ID: <524151AF.2040408@ti.com> Date: Tue, 24 Sep 2013 14:17:43 +0530 From: Sricharan R User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 To: Javier Martinez Canillas CC: Tony Lindgren , Santosh Shilimkar , Kevin Hilman , Linus Walleij , Stephen Warren , Lars Poeschel , Grant Likely , Mark Rutland , Ian Campbell , Kumar Gala , Pawel Moll , Tomasz Figa , Enric Balletbo i Serra , Jean-Christophe PLAGNIOL-VILLARD , Balaji T K , Jon Hunter , , , , Subject: Re: [RFC] gpio/omap: auto-setup a GPIO when used as an IRQ References: <1379860848-29020-1-git-send-email-javier.martinez@collabora.co.uk> <20130923164519.GF2684@atomide.com> <524073BC.9080907@collabora.co.uk> <20130923170724.GG2684@atomide.com> <524141A6.2090701@ti.com> <5241454E.2050602@collabora.co.uk> In-Reply-To: <5241454E.2050602@collabora.co.uk> 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: 2849 Lines: 77 On Tuesday 24 September 2013 01:24 PM, Javier Martinez Canillas wrote: > On 09/24/2013 09:39 AM, Sricharan R wrote: >> Hi, >> On Monday 23 September 2013 10:37 PM, Tony Lindgren wrote: >>> * Javier Martinez Canillas [130923 10:09]: >>>> On 09/23/2013 06:45 PM, Tony Lindgren wrote: >>>>> Hmm does this still work for legacy platform data based >>>>> drivers that are doing gpio_request() first? >>>>> >>>> Yes it still work when booting using board files. I tested on my OMAP3 board and >>>> it worked in both DT and legacy booting mode. >>> OK great. >>> >>>>> And what's the path for clearing things for PM when free_irq() >>>>> gets called? It seems that this would leave the GPIO bank >>>>> enabled causing a PM regression? >>>>> >>>> Indeed, I did set bank->mod_usage |= 1 << offset so the bank is enabled if the >>>> device goes to suspended and then resumed but I completely forget about the >>>> clearing path when the IRQ is freed. >>>> >>>> Which makes me think that we should probably maintain two usage variables, one >>>> for GPIO and another one for IRQ and check both of them on the suspend/resume pm >>>> functions. >>> Yes that it seems that they should be treated separately. >> To understand, why cant the flag be cleared in gpio_irq_shutdown ? > Hi Sricharan, > > Without this patch today drivers do this: > > gpio_request(gpio, "foo IRQ"); // bank->mod_usage |= 1 << offset > gpio_direction_input(gpio); > > and then request a IRQ with: > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); > > later on its cleanup path: > > free_irq(irq, dev); > gpio_free(gpio) // bank->mod_usage &= ~(1 << offset); > > So if you clear the flag on gpio_irq_shutdown then bank module won't be enabled > after a suspend making drivers using the GPIO after freeing the IRQ to fail. > > So the idea is to have something like this: > > a) Drivers that request both the GPIO and IRQ > > gpio_request(gpio, "foo IRQ"); // bank->mod_usage |= 1 << offset > gpio_direction_input(gpio); > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); // bank->irq_usage |= 1 << offset > > free_irq(irq, dev); // bank->irq_usage &= ~(1 << offset); > gpio_free(gpio) // bank->mod_usage &= ~(1 << offset); > > b) Drivers that just request the IRQ: > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); // bank->irq_usage |= 1 << offset > free_irq(irq, dev); // bank->irq_usage &= ~(1 << offset); > > So irq_usage or mod_usage is set means that the bank has to be enabled and if > both are not set means that the bank module can be disabled. > Ok get it. Thanks. Regards, Sricharan -- 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/