From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Figa Subject: Re: [PATCH] pinctrl: samsung: Allow pin value to be initialized using pinfunc. Date: Thu, 05 Dec 2013 18:03:02 +0100 Message-ID: <1475204.PCyxT0KMui@amdc1227> References: <1384881351-10782-1-git-send-email-t.figa@samsung.com> <1502243.eRBlCfUhTO@amdc1227> <52A0AEB4.7090909@bracey.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit Return-path: In-reply-to: <52A0AEB4.7090909@bracey.fi> Sender: linux-samsung-soc-owner@vger.kernel.org To: Kevin Bracey Cc: Mark Brown , Linus Walleij , Kyungmin Park , "devicetree@vger.kernel.org" , linux-samsung-soc , Heiko =?ISO-8859-1?Q?St=FCbner?= , Stephen Warren , Doug Anderson , "linux-kernel@vger.kernel.org" , Kukjin Kim , Thomas Abraham , "linux-arm-kernel@lists.infradead.org" , Marek Szyprowski List-Id: devicetree@vger.kernel.org On Thursday 05 of December 2013 18:49:56 Kevin Bracey wrote: > On 05/12/2013 17:11, Tomasz Figa wrote: > > On Thursday 05 of December 2013 15:07:47 Mark Brown wrote: > >> On Tue, Dec 03, 2013 at 10:29:42AM +0100, Linus Walleij wrote: > >> > >>> So a suggested patch to support weak hogs would be interesting > >>> to look at. Can you provide details on how you think this would > >>> work? > >> Or should we be going and applying the default state to all devices on > >> init without worrying about a driver appearing? > > If a device isn't used, then it's often better to configure the pins for > > a different function, such as GPIO, to minimize leakage current. > > > > And there can also be mutually-exclusive drivers choosing different > default states for the same pin. I think you do need a separate "safe" > indicator. That's not quite true, as on a single board you should rather have a single device node with "okay" status referencing given set of pins. Still, I think that a separate safe state is the way to go. > > My current thought is that a late-init "make safe all unclaimed pins" > pass would make sense - you can't really mess with pins in an automated > fashion on init, as it can mess up bootloader->driver handover. There > already exist late-init "turn off all unclaimed clocks" (at least on > shmobile) That's a feature of Common Clock Framework. > and "turn off all unclaimed regulators", and it would fit that > model. Maybe that's the way to do it. I need to think a bit more on this, especially considering our (Samsung's) use cases. Best regards, Tomasz