From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Chen Subject: Re: [PATCH 2/8] power: add power sequence library Date: Fri, 3 Feb 2017 16:16:15 +0800 Message-ID: <20170203081614.GA24614@b29397-desktop> References: <1483425211-14473-1-git-send-email-peter.chen@nxp.com> <1483425211-14473-3-git-send-email-peter.chen@nxp.com> <20170201080817.GD17968@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170201080817.GD17968@kroah.com> Sender: linux-pm-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" , Peter Chen , Alan Stern , Ulf Hansson , Mark Brown , Sebastian Reichel , Rob Herring , Shawn Guo , "Rafael J. Wysocki" , Dmitry Eremin-Solenikov , Heiko Stuebner , "linux-arm-kernel@lists.infradead.org" , p.zabel@pengutronix.de, "devicetree@vger.kernel.org" , Pawel Moll , Mark Rutland , "open list:ULTRA-WIDEBAND (UWB) SUBSYSTEM:" , Arnd Bergmann , Sas List-Id: devicetree@vger.kernel.org On Wed, Feb 01, 2017 at 09:08:17AM +0100, Greg Kroah-Hartman wrote: > On Wed, Feb 01, 2017 at 12:10:17AM +0100, Rafael J. Wysocki wrote: > > On Tue, Jan 3, 2017 at 7:33 AM, Peter Chen wrote: > > > We have an well-known problem that the device needs to do some power > > > sequence before it can be recognized by related host, the typical > > > example like hard-wired mmc devices and usb devices. > > > > > > This power sequence is hard to be described at device tree and handled by > > > related host driver, so we have created a common power sequence > > > library to cover this requirement. The core code has supplied > > > some common helpers for host driver, and individual power sequence > > > libraries handle kinds of power sequence for devices. The pwrseq > > > librares always need to allocate extra instance for compatible > > > string match. > > > > > > pwrseq_generic is intended for general purpose of power sequence, which > > > handles gpios and clocks currently, and can cover other controls in > > > future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off > > > if only one power sequence is needed, else call of_pwrseq_on_list > > > /of_pwrseq_off_list instead (eg, USB hub driver). > > > > > > For new power sequence library, it can add its compatible string > > > to pwrseq_of_match_table, then the pwrseq core will match it with > > > DT's, and choose this library at runtime. > > > > > > Signed-off-by: Peter Chen > > > Tested-by: Maciej S. Szmigiero > > > Tested-by Joshua Clayton > > > Reviewed-by: Matthias Kaehlcke > > > Tested-by: Matthias Kaehlcke > > > > Quite honestly, I have a really hard time with trying to follow this > > code and the total lack of documentation makes it even harder. Sorry about that, Is it ok I add the design doc at: Documentation/power/power-sequence/design.rst? > > particular, the generic power sequence code is not even commented at > > all, The generic power sequence code just implements the APIs which are called at power/pwrseq/core.c, and those API are commented at include/linux/power/pwrseq.h. Anyway, I will add more comments at it. -- Best Regards, Peter Chen