From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [RFC PATCH v2 09/12] gpiolib: Identify GPIO descriptor arrays with direct mapping Date: Tue, 7 Aug 2018 19:14:20 +0200 Message-ID: <20180807191420.04431e8e@bbrezillon> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180806222918.12644-1-jmkrzyszt@gmail.com> <20180806222918.12644-10-jmkrzyszt@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180806222918.12644-10-jmkrzyszt@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Janusz Krzysztofik Cc: Linus Walleij , Jonathan Corbet , Miquel Raynal , Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut , Tony Lindgren , Aaro Koskinen , linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-mtd@lists.infradead.org, linux-doc@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-gpio@vger.kernel.org On Tue, 7 Aug 2018 00:29:15 +0200 Janusz Krzysztofik wrote: > Certain GPIO array lookup results may map directly to GPIO pins of a > single GPIO chip in hardware order. If that condition is recognized > and handled efficiently, significant performance gain of get/set array > functions may be possible. > > While processing a request for an array of GPIO descriptors, verify if > the descriptors just collected represent consecutive pins of a single > GPIO chip. Pass that information with the array to the caller so it > can benefit from enhanced performance as soon as bitmap based get/set > array functions which can make efficient use of that are available. > > Signed-off-by: Janusz Krzysztofik > --- > Documentation/driver-api/gpio/consumer.rst | 4 +++- > drivers/gpio/gpiolib.c | 14 ++++++++++++++ > include/linux/gpio/consumer.h | 1 + > 3 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst > index aa03f389d41d..38a990b5f3b6 100644 > --- a/Documentation/driver-api/gpio/consumer.rst > +++ b/Documentation/driver-api/gpio/consumer.rst > @@ -109,11 +109,13 @@ For a function using multiple GPIOs all of those can be obtained with one call:: > enum gpiod_flags flags) > > This function returns a struct gpio_descs which contains an array of > -descriptors:: > +descriptors. It may also contain a valid descriptor of a single GPIO chip in > +case the array strictly matches pin hardware layout of the chip:: > > struct gpio_descs { > unsigned int ndescs; > struct gpio_desc *desc[]; > + struct gpio_chip *chip; chip is placed at the beginning of the struct in the real code, which is expected since putting it at the end won't work because of the desc[] declaration. ... > diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h > index 21ddbe440030..862ee027a02f 100644 > --- a/include/linux/gpio/consumer.h > +++ b/include/linux/gpio/consumer.h > @@ -22,6 +22,7 @@ struct gpio_desc; > * gpiod_get_array(). > */ > struct gpio_descs { > + struct gpio_chip *chip; > unsigned int ndescs; > struct gpio_desc *desc[]; > }; From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 9AD4F7E3B8 for ; Tue, 7 Aug 2018 17:14:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388943AbeHGTaA (ORCPT ); Tue, 7 Aug 2018 15:30:00 -0400 Received: from mail.bootlin.com ([62.4.15.54]:37061 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390121AbeHGTaA (ORCPT ); Tue, 7 Aug 2018 15:30:00 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 080D5209D9; Tue, 7 Aug 2018 19:14:39 +0200 (CEST) Received: from bbrezillon (91-160-177-164.subs.proxad.net [91.160.177.164]) by mail.bootlin.com (Postfix) with ESMTPSA id C5A4E20799; Tue, 7 Aug 2018 19:14:19 +0200 (CEST) Date: Tue, 7 Aug 2018 19:14:20 +0200 From: Boris Brezillon To: Janusz Krzysztofik Cc: Linus Walleij , Jonathan Corbet , Miquel Raynal , Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut , Tony Lindgren , Aaro Koskinen , linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-mtd@lists.infradead.org, linux-doc@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 09/12] gpiolib: Identify GPIO descriptor arrays with direct mapping Message-ID: <20180807191420.04431e8e@bbrezillon> In-Reply-To: <20180806222918.12644-10-jmkrzyszt@gmail.com> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180806222918.12644-1-jmkrzyszt@gmail.com> <20180806222918.12644-10-jmkrzyszt@gmail.com> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, 7 Aug 2018 00:29:15 +0200 Janusz Krzysztofik wrote: > Certain GPIO array lookup results may map directly to GPIO pins of a > single GPIO chip in hardware order. If that condition is recognized > and handled efficiently, significant performance gain of get/set array > functions may be possible. > > While processing a request for an array of GPIO descriptors, verify if > the descriptors just collected represent consecutive pins of a single > GPIO chip. Pass that information with the array to the caller so it > can benefit from enhanced performance as soon as bitmap based get/set > array functions which can make efficient use of that are available. > > Signed-off-by: Janusz Krzysztofik > --- > Documentation/driver-api/gpio/consumer.rst | 4 +++- > drivers/gpio/gpiolib.c | 14 ++++++++++++++ > include/linux/gpio/consumer.h | 1 + > 3 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst > index aa03f389d41d..38a990b5f3b6 100644 > --- a/Documentation/driver-api/gpio/consumer.rst > +++ b/Documentation/driver-api/gpio/consumer.rst > @@ -109,11 +109,13 @@ For a function using multiple GPIOs all of those can be obtained with one call:: > enum gpiod_flags flags) > > This function returns a struct gpio_descs which contains an array of > -descriptors:: > +descriptors. It may also contain a valid descriptor of a single GPIO chip in > +case the array strictly matches pin hardware layout of the chip:: > > struct gpio_descs { > unsigned int ndescs; > struct gpio_desc *desc[]; > + struct gpio_chip *chip; chip is placed at the beginning of the struct in the real code, which is expected since putting it at the end won't work because of the desc[] declaration. ... > diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h > index 21ddbe440030..862ee027a02f 100644 > --- a/include/linux/gpio/consumer.h > +++ b/include/linux/gpio/consumer.h > @@ -22,6 +22,7 @@ struct gpio_desc; > * gpiod_get_array(). > */ > struct gpio_descs { > + struct gpio_chip *chip; > unsigned int ndescs; > struct gpio_desc *desc[]; > }; -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@bootlin.com (Boris Brezillon) Date: Tue, 7 Aug 2018 19:14:20 +0200 Subject: [RFC PATCH v2 09/12] gpiolib: Identify GPIO descriptor arrays with direct mapping In-Reply-To: <20180806222918.12644-10-jmkrzyszt@gmail.com> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180806222918.12644-1-jmkrzyszt@gmail.com> <20180806222918.12644-10-jmkrzyszt@gmail.com> Message-ID: <20180807191420.04431e8e@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 7 Aug 2018 00:29:15 +0200 Janusz Krzysztofik wrote: > Certain GPIO array lookup results may map directly to GPIO pins of a > single GPIO chip in hardware order. If that condition is recognized > and handled efficiently, significant performance gain of get/set array > functions may be possible. > > While processing a request for an array of GPIO descriptors, verify if > the descriptors just collected represent consecutive pins of a single > GPIO chip. Pass that information with the array to the caller so it > can benefit from enhanced performance as soon as bitmap based get/set > array functions which can make efficient use of that are available. > > Signed-off-by: Janusz Krzysztofik > --- > Documentation/driver-api/gpio/consumer.rst | 4 +++- > drivers/gpio/gpiolib.c | 14 ++++++++++++++ > include/linux/gpio/consumer.h | 1 + > 3 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst > index aa03f389d41d..38a990b5f3b6 100644 > --- a/Documentation/driver-api/gpio/consumer.rst > +++ b/Documentation/driver-api/gpio/consumer.rst > @@ -109,11 +109,13 @@ For a function using multiple GPIOs all of those can be obtained with one call:: > enum gpiod_flags flags) > > This function returns a struct gpio_descs which contains an array of > -descriptors:: > +descriptors. It may also contain a valid descriptor of a single GPIO chip in > +case the array strictly matches pin hardware layout of the chip:: > > struct gpio_descs { > unsigned int ndescs; > struct gpio_desc *desc[]; > + struct gpio_chip *chip; chip is placed at the beginning of the struct in the real code, which is expected since putting it at the end won't work because of the desc[] declaration. ... > diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h > index 21ddbe440030..862ee027a02f 100644 > --- a/include/linux/gpio/consumer.h > +++ b/include/linux/gpio/consumer.h > @@ -22,6 +22,7 @@ struct gpio_desc; > * gpiod_get_array(). > */ > struct gpio_descs { > + struct gpio_chip *chip; > unsigned int ndescs; > struct gpio_desc *desc[]; > };