From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Thu, 28 Jul 2016 19:53:30 +0200 Subject: [PATCH v4] ARM: dts: sun8i: Add dts file for Olimex A33-OLinuXino In-Reply-To: <1604486.mrBvLz4HRZ@linux-cigu> References: <1469450243-19138-1-git-send-email-stefan.mavrodiev@gmail.com> <30014119.IrjfP0xFry@linux-cigu> <20160727062146.GA6560@lukather> <1604486.mrBvLz4HRZ@linux-cigu> Message-ID: <20160728175330.GC6682@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 27, 2016 at 01:02:41PM +0300, stefan.mavrodiev at gmail.com wrote: > On Wednesday, July 27, 2016 8:21:46 AM EEST Maxime Ripard wrote: > > On Wed, Jul 27, 2016 at 08:12:29AM +0300, stefan.mavrodiev at gmail.com wrote: > > > > > +®_dcdc1 { > > > > > + regulator-always-on; > > > > > + regulator-min-microvolt = <3300000>; > > > > > + regulator-max-microvolt = <3300000>; > > > > > + regulator-name = "vcc-dsi"; > > > > > +}; > > > > > > > > What is it used for? Is it really necessary to keep it on at all time? > > > > > > I think so. > > > This is the supply for the MMC. > > > > Then it's poorly named, and you should tie it to the MMC, and remove > > the always-on if it's only used by the mmc. always-on is supposed to > > be for regulators that shouldn't but turned off for the system to stay > > running. Some MMC regulator doesn't fit that description. > > It's named upon the A33 power pin - "VCC-DSI". Usually, it's based on the name of the output in the schematics, precisely because, from one board to another, it might have different usage. > If I remove "always-on" the board still will work, since dcdc1 is tied to > mmc0. > vmmc-supply = <®_dcdc1>; > > We assume this voltage will be always present and there are some pullups that > are tied to it (on i2c0 and i2c1 bus). In this case should I remove "always- > on" from the regulator node? No, you should just tie that regulator to the i2c buses as well. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: not available URL: