Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932112AbbGJJ36 (ORCPT ); Fri, 10 Jul 2015 05:29:58 -0400 Received: from mail-wg0-f42.google.com ([74.125.82.42]:36721 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752462AbbGJJ3q (ORCPT ); Fri, 10 Jul 2015 05:29:46 -0400 MIME-Version: 1.0 In-Reply-To: References: <1435754753-31307-1-git-send-email-tomeu.vizoso@collabora.com> <1435754753-31307-2-git-send-email-tomeu.vizoso@collabora.com> From: Tomeu Vizoso Date: Fri, 10 Jul 2015 11:29:25 +0200 X-Google-Sender-Auth: 4QW5eTLlX05EZ8hcOABTqUFdf-Y Message-ID: Subject: Re: [PATCH v1 1/3] gpio: defer probe if pinctrl cannot be found To: Rob Herring Cc: "linux-kernel@vger.kernel.org" , "linux-gpio@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-tegra@vger.kernel.org" , Linus Walleij , Grant Likely , Rob Herring , Alexandre Courbot Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2394 Lines: 58 On 1 July 2015 at 19:36, Rob Herring wrote: > On Wed, Jul 1, 2015 at 7:45 AM, Tomeu Vizoso wrote: >> When an OF node has a pin range for its GPIOs, return -EPROBE_DEFER if >> the pin controller isn't available. >> >> Otherwise, the GPIO range wouldn't be set at all unless the pin >> controller probed always before the GPIO chip. >> >> With this change, the probe of the GPIO chip will be deferred and will >> be retried at a later point, hopefully once the pin controller has been >> registered and probed already. > > This will break cases where the pinctrl driver does not exist, but the > DT contains pinctrl bindings. We can have similar problems already > with clocks though. However, IMO this problem is a bit different in > that pinctrl is more likely entirely optional while clocks are often > required. You may do all pin setup in bootloader/firmware on some > boards and not others. Of course then why put pinctrl in the DT in > that case? They could be present just due to how chip vs. board dts > files are structured. I see. My instinct tells me that it would be better if the gpio-ranges property was set in the board dts, but I don't really know what each mach does with its DTSs. > We could address this by simply marking the pin controller node > disabled. However, ... > >> @@ -361,7 +361,7 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip) >> >> pctldev = of_pinctrl_get(pinspec.np); >> if (!pctldev) >> - break; >> + return -EPROBE_DEFER; > > But you cannot distinguish that case here. I think of_pinctrl_get > needs to set the error code appropriately. Why not? I was thinking of just doing this before we call of_pinctrl_get(): if (!of_device_is_available(pinspec.np)) continue; Thanks, Tomeu > Rob > -- > 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/ -- 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/