Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755256Ab0BIRRJ (ORCPT ); Tue, 9 Feb 2010 12:17:09 -0500 Received: from mail-iw0-f171.google.com ([209.85.223.171]:40978 "EHLO mail-iw0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754206Ab0BIRRF convert rfc822-to-8bit (ORCPT ); Tue, 9 Feb 2010 12:17:05 -0500 MIME-Version: 1.0 In-Reply-To: <20100205203232.GA1475@oksana.dev.rtsoft.ru> References: <20100205203201.GA32281@oksana.dev.rtsoft.ru> <20100205203232.GA1475@oksana.dev.rtsoft.ru> From: Grant Likely Date: Tue, 9 Feb 2010 10:16:44 -0700 X-Google-Sender-Auth: d61d07d1bdcbcb23 Message-ID: Subject: Re: [PATCH 1/4] gpiolib: Introduce chip addition/removal notifier To: Anton Vorontsov Cc: David Brownell , Andrew Morton , Bill Gatliff , Dmitry Eremin-Solenikov , Benjamin Herrenschmidt , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3055 Lines: 77 On Fri, Feb 5, 2010 at 1:32 PM, Anton Vorontsov wrote: > Some platforms (e.g. OpenFirmware) want to know when a particular chip > added or removed, so that the platforms could add their specifics for > non-platform devices, like I2C or SPI GPIO chips. > > This patch implements the notifier for chip addition and removal events. > > Signed-off-by: Anton Vorontsov > --- > ?drivers/gpio/gpiolib.c ? ? | ? 14 ++++++++++++++ > ?include/asm-generic/gpio.h | ? ?8 ++++++++ > ?2 files changed, 22 insertions(+), 0 deletions(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 350842a..375c03a 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -9,6 +9,7 @@ > ?#include > ?#include > ?#include > +#include > > > ?/* Optional implementation infrastructure for GPIO interfaces. > @@ -1029,6 +1030,9 @@ static inline void gpiochip_unexport(struct gpio_chip *chip) > > ?#endif /* CONFIG_GPIO_SYSFS */ > > +BLOCKING_NOTIFIER_HEAD(gpio_notifier); > +EXPORT_SYMBOL_GPL(gpio_notifier); > + > ?/** > ?* gpiochip_add() - register a gpio_chip > ?* @chip: the chip to register, with chip->base initialized > @@ -1103,6 +1107,9 @@ fail: > ? ? ? ? ? ? ? ?pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n", > ? ? ? ? ? ? ? ? ? ? ? ?chip->base, chip->base + chip->ngpio - 1, > ? ? ? ? ? ? ? ? ? ? ? ?chip->label ? : "generic"); > + ? ? ? else > + ? ? ? ? ? ? ? blocking_notifier_call_chain(&gpio_notifier, > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?GPIO_NOTIFY_CHIP_ADDED, chip); Rather than doing an else block which will need to be reworked if/when any additional code is added to the bottom of this routine, please rework the if() block to bail on failure instead of implicitly falling through to the return statement. Otherwise, this patch looks okay to me, so you can go ahead and add my: Acked-by: Grant Likely *however* (and don't kill me for saying this because I know I suggested the notifier approach in the first place). Looking at the whole patch series, the notifier call adds a lot of code for very little gain. If you dropped just the notifier bits (but left the rest of the series the same), then the the of gpio bits would be considerably simpler, and the only impact on the core gpiolib would be the addition of an of_gpiochip_register_simple() and of_gpiochip_unregister() hooks that will be conditionally compiled. And to address one of my previous concerns, I've got no problem with the automatic registration of GPIO devices for OF usage, as long as of-aware drivers have the option of overriding the simple defaults when needed. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. -- 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/