From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757987Ab3FLShV (ORCPT ); Wed, 12 Jun 2013 14:37:21 -0400 Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:45401 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755998Ab3FLShT (ORCPT ); Wed, 12 Jun 2013 14:37:19 -0400 X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 50.131.214.131 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX1/H41/UN0gYw9FE6Cie4Odn Date: Wed, 12 Jun 2013 11:37:16 -0700 From: Tony Lindgren To: Linus Walleij Cc: Stephen Warren , Kevin Hilman , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linus Walleij , Ulf Hansson Subject: Re: [PATCH] pinctrl: document the pinctrl PM states Message-ID: <20130612183716.GW8164@atomide.com> References: <1370980749-15383-1-git-send-email-linus.walleij@stericsson.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1370980749-15383-1-git-send-email-linus.walleij@stericsson.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Linus Walleij [130611 13:05]: > From: Linus Walleij > > This document snippet tries to be helpful and define the pin > PM states and helpers, and how they should be used to create > some kind of common ontology around this. > > Cc: Ulf Hansson > Cc: Kevin Hilman > Cc: Tony Lindgren > Signed-off-by: Linus Walleij > --- > Documentation/pinctrl.txt | 118 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 118 insertions(+) > > diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt > index f6e664b..a34ea92 100644 > --- a/Documentation/pinctrl.txt > +++ b/Documentation/pinctrl.txt > @@ -1196,6 +1196,124 @@ registered. Thus make sure that the error path in your driver gracefully > cleans up and is ready to retry the probing later in the startup process. > > > +Default and power management related states > +=========================================== > + > +As mentioned earlier the device core will automatically try to obtain a > +pinctrl handle and activate the "default" state on all drivers. > + > +However, for power management and power saving, it is sometimes necessary > +to switch pin states at runtime. Electrically speaking this involves > +for example reconfigure some pins to be grounded or pulled-down when the > +system as a whole goes to sleep, or a pull-up could be turned off when pins > +are idle, reducing leak current. > + > +To help out with this, if CONFIG_PM is selected in the Kconfig, three > +additional states will also be obtained by the driver core and cached > +there: > + > +"active" this is indended as an explicit active state, if the "default" > + state is not synonymous with the active one. > + > +"idle" this is a state that is relaxing the pins when the system as a > + whole is up and running, but these particular pins are unused. > + > +"sleep" this is a state that is used when the whole system goes to > + suspend, becomes uninteractive, unresponsive to anything but > + specific wake-up events. In the cases I've seen "idle" and "sleep" are the same. But it sounds like other people's hardware have different needs and it's optional so: Acked-by: Tony Lindgren