From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lothar =?UTF-8?B?V2HDn21hbm4=?= Subject: Re: [RCF PATCH,v2,2/2] pwm: imx: Configure output to GPIO in disabled state Date: Fri, 16 Nov 2018 08:34:30 +0100 Message-ID: <20181116083430.7f1d8452@ipc1.ka-ro> References: <20181107093355.e4n3irrnkybqsjvc@pengutronix.de> <20181107150125.7cpd4v5t7yi2254c@pengutronix.de> <4fbb7307-df01-d7bd-f2e2-e05e6d17807d@ysoft.com> <20181108191855.zuon3ecv4yjfbs7g@pengutronix.de> <283cfef3-16d0-8bd4-e306-6e34d44c3a86@ysoft.com> <20181109165555.vqbiwh4hlcnozdna@pengutronix.de> <20181114113449.GB2620@ulmo> <20181114215120.vddykljqyavm64wj@pengutronix.de> <20181115152545.GA8611@ulmo> <20181115203733.qvonika6yhn2bsnb@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20181115203733.qvonika6yhn2bsnb@pengutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: Uwe =?UTF-8?B?S2xlaW5lLUvDtm5pZw==?= Cc: Thierry Reding , =?UTF-8?B?Vm9rw6HEjQ==?= Michal , Mark Rutland , "devicetree@vger.kernel.org" , "linux-pwm@vger.kernel.org" , Lukasz Majewski , "linux-kernel@vger.kernel.org" , Rob Herring , "kernel@pengutronix.de" , Fabio Estevam , Linus Walleij List-Id: devicetree@vger.kernel.org Uwe Kleine-König wrote: > Hello Thierry, > > On Thu, Nov 15, 2018 at 04:25:45PM +0100, Thierry Reding wrote: > > On Wed, Nov 14, 2018 at 10:51:20PM +0100, Uwe Kleine-König wrote: > > > On Wed, Nov 14, 2018 at 12:34:49PM +0100, Thierry Reding wrote: [...] > > > Also dts writes don't need to lookup the needed GPIO numbers and pinctrl. > > > > Just to clarify: I don't think that we need to get the GPIO number > > involved in this case, because we don't have to reconfigure the pin as > > GPIO to make this work. The only reason that Michal's proposal did that > > is because that was believed to be necessary. But if the pin can just be > > configured with a 100k pull-up, that's enough to pull the pin high when > > we need it. > > Unless the gpio happens to be configured as output at the wrong value. > Further I'm not sure if the pwm in disabled state actively pulls to 0 > and if in this state the PU of the pin is good enough to ensure a one > here. That would need verification first. > No. You can disable the output driver via pinctrl, so that only the selected pull-up/down is relevant. The pin function and GPIO register settings don't matter at all in this case. Lothar Waßmann -- ___________________________________________________________ Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10 Geschäftsführer: Matthias Kaussen Handelsregistereintrag: Amtsgericht Aachen, HRB 4996 www.karo-electronics.de | info@karo-electronics.de ___________________________________________________________