From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Behme Subject: Re: [PATCH v2] Documentation: gpio: consumer: describe the con_id parameter Date: Sat, 25 Jul 2015 09:15:49 +0200 Message-ID: <55B337A5.4020207@gmail.com> References: <1437200647-5138-1-git-send-email-dirk.behme@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f177.google.com ([209.85.212.177]:33787 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513AbbGYHPw (ORCPT ); Sat, 25 Jul 2015 03:15:52 -0400 Received: by wicmv11 with SMTP id mv11so84401016wic.0 for ; Sat, 25 Jul 2015 00:15:51 -0700 (PDT) In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Alexandre Courbot Cc: "linux-gpio@vger.kernel.org" , Alexandre Courbot On 21.07.2015 07:12, Alexandre Courbot wrote: > On Sat, Jul 18, 2015 at 3:24 PM, Dirk Behme wrote: >> The con_id parameter has to match the GPIO description and is automatically >> extended by the GPIO suffix if not NULL. I had to look into the code to >> understand this and properly find the GPIO I've been looking for, so document >> this. >> >> Signed-off-by: Dirk Behme >> Acked-by: Alexandre Courbot >> --- >> Changes in v2: Incorporate the review comments from Alexandre. >> >> Documentation/gpio/consumer.txt | 13 +++++++++++++ >> 1 file changed, 13 insertions(+) >> >> diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt >> index 75542b9..5f7437b 100644 >> --- a/Documentation/gpio/consumer.txt >> +++ b/Documentation/gpio/consumer.txt >> @@ -39,6 +39,19 @@ device that displays digits), an additional index argument can be specified: >> const char *con_id, unsigned int idx, >> enum gpiod_flags flags) >> >> +The con_id string parameter has to be either NULL or the prefix of the GPIO >> +suffixes ("gpios" or "gpio", automatically looked up by the gpiod functions >> +internally): >> + >> +* If the GPIO description is just named with one of the GPIO suffixes >> + ("gpios" or "gpio"), use NULL. >> +* If the GPIO description is prefixed with anything, e.g. "reset-gpios", use the >> + prefix without the "-" as con_id parameter (in this example "reset"). >> + >> +In case con_id is not NULL, the GPIO subsystem prefixes the GPIO suffix >> +("gpios" or "gpio") with the string passed in con_id to get the resulting string >> +(snprintf(... "%s-%s", con_id, gpio_suffixes[]). > > Ah, there is still an issue with this description. It is correct as > far as GPIOs are assigned by the device tree ; but it turns out that > we have two other ways of assigning GPIOs: ACPI and platform data. > Have a look at the board.txt file which describes how this works. And > actually, instead of repeating the same stuff in consumer.txt, maybe > we can just redirect the reader to the other file? Please have a look to http://article.gmane.org/gmane.linux.kernel.gpio/9816 http://article.gmane.org/gmane.linux.kernel.gpio/9815 They should replace this patch, then. Best regards Dirk