From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Daney Subject: Re: [PATCH] of/gpio: Define OF_GPIO_OPEN_DRAIN flag for Open Drain outputs. Date: Tue, 11 Feb 2014 10:51:51 -0800 Message-ID: <52FA7147.20607@caviumnetworks.com> References: <1392069908-22017-1-git-send-email-ddaney.cavm@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Alexandre Courbot Cc: David Daney , Grant Likely , Rob Herring , "devicetree@vger.kernel.org" , Linus Walleij , "linux-gpio@vger.kernel.org" , Linux Kernel Mailing List , David Daney List-Id: linux-gpio@vger.kernel.org On 02/10/2014 08:31 PM, Alexandre Courbot wrote: > On Tue, Feb 11, 2014 at 7:05 AM, David Daney wrote: >> From: David Daney >> >> When we have a GPIO pin connected to an open-drain network, we want a >> standard way of specifying this in the device tree. So we choose bit >> 1 of the flag field to indicate open drain. >> >> A typical use case would be something like: >> >> enum of_gpio_flags f; >> . >> . >> . >> reset_gpio = of_get_named_gpio_flags(node, "reset", 0, &f); >> . >> . >> . >> ret = gpio_request_one(reset_gpio, >> (f & OF_GPIO_OPEN_DRAIN) ? GPIOF_OPEN_DRAIN : 0, >> "reset"); >> . >> . >> . >> gpio_direction_output(reset_gpio, 1); >> gpio_set_value(reset_gpio, 0); >> msleep(20); >> gpio_set_value(reset_gpio, 1); > > This is also useful for gpiod_get(). However, while you are at it, > could you also add a flag for the OF_GPIO_OPEN_SOURCE property? My joy > would be complete if you could also take the time to update > of_find_gpio() to pass these new flags back to the caller as it > already does for OF_GPIO_ACTIVE_LOW. > > Then you could even switch your use-case to the gpiod interface and > not bother with passing these flags by yourself anymore. Just sayin'. > ;) Thanks for the suggestion. I will send a revised patch set for your consideration. David Daney