From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [RFC 1/2] PM / suspend: Add platform_suspend_target_state() Date: Sun, 16 Jul 2017 15:41:16 +0200 Message-ID: <20170716134116.wxwb3gevbhlereij@piout.net> References: <20170622085102.mpk7vxodpgxtrlfd@piout.net> <2497538.J9F6XFeBfd@aspire.rjw.lan> <20170715062838.GA20741@amd> <5864280.u6UQBsuXnA@aspire.rjw.lan> <20170715164626.GA1373@amd> <1a5ef0ae-16f3-5a61-ae4e-083664cb30c0@gmail.com> <20170715183358.4bnhshokalyulswz@piout.net> <20170706031819.GD12954@xo-6d-61-c0.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.free-electrons.com ([62.4.15.54]:57661 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274AbdGPNli (ORCPT ); Sun, 16 Jul 2017 09:41:38 -0400 Content-Disposition: inline In-Reply-To: <20170706031819.GD12954@xo-6d-61-c0.localdomain> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Pavel Machek Cc: Florian Fainelli , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Ulf Hansson , Daniel Lezcano , linux-pm , Thibaud Cornic , JB , Mason , Kevin Hilman , Linux ARM On 06/07/2017 at 05:18:19 +0200, Pavel Machek wrote: > On Sat 2017-07-15 20:33:58, Alexandre Belloni wrote: > > On 15/07/2017 at 10:20:27 -0700, Florian Fainelli wrote: > > > > We already have > > > > > > > > struct regulator_state { > > > > int uV; /* suspend voltage */ > > > > unsigned int mode; /* suspend regulator operating mode */ > > > > int enabled; /* is regulator enabled in this suspend state */ > > > > int disabled; /* is the regulator disabled in this suspend state */ > > > > }; > > > > > > > > * struct regulation_constraints - regulator operating constraints. > > > > * @state_disk: State for regulator when system is suspended in disk > > > > * mode. > > > > * @state_mem: State for regulator when system is suspended in mem > > > > * mode. > > > > * @state_standby: State for regulator when system is suspended in > > > > * standby > > > > * mode. > > > > > > > > . So it seems that maybe we should tell the drivers if we are entering > > > > "state_mem" or "state_standby" (something I may have opposed, sorry), > > > > then the driver can get neccessary information from regulator > > > > framework. > > > > > > OK, so what would be the mechanism to tell these drivers about the > > > system wide suspend state they are entering if it is not via > > > platform_suspend_target_state()? > > > > > > Keep in mind that regulators might be one aspect of what could be > > > causing the platform to behave specifically in one suspend state vs. > > > another, but there could be pieces of HW within the SoC that can't be > > > described with power domains, voltage islands etc. that would still have > > > inherent suspend states properties (like memory retention, pin/pad > > > controls etc. etc). We still need some mechanism, possibly centralized > > > > > > > I concur, the regulator stuff is one aspect of one of our suspend state > > (cutting VDDcore). But we have another state where the main clock (going > > to the IPs) is going from a few hundred MHz to 32kHz. This is currently > > handled by calling at91_suspend_entering_slow_clock(). I think it is > > important to take that into account so we can remove this hack from the > > kernel. > > Cure should not be worse then the disease... and it is in this case. > > For clocks, take a look at clock framework, perhaps it already has "clock_will_be_suspended" > as regulator framework had. If not, implement it. > See Rafael's comment, currently, the clock framework can't say whether the clock will change because it doesn't know anything about the suspend target. > Same with memory retention, pin/pad controls. > Same here. -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com