From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754261AbeEaUEm (ORCPT ); Thu, 31 May 2018 16:04:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:44194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754071AbeEaUEk (ORCPT ); Thu, 31 May 2018 16:04:40 -0400 X-Google-Smtp-Source: ADUXVKJhIFa9pWVcfa4Kxo4I+aqOmUpGjIDgnXrGFccR94Ev6NA0DbnDdsA1L8Jw6Xi4TsHY8+5ZC3EXdm7iV27azR8= MIME-Version: 1.0 In-Reply-To: <20180531183404.GB88063@google.com> References: <20180525203043.249193-1-mka@chromium.org> <20180525203043.249193-11-mka@chromium.org> <20180531163159.GA4369@rob-hp-laptop> <20180531183404.GB88063@google.com> From: Rob Herring Date: Thu, 31 May 2018 15:04:18 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 10/11] dt-bindings: misc: add bindings for throttler To: Matthias Kaehlcke Cc: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Arnd Bergmann , Greg Kroah-Hartman , Mark Rutland , linux-pm@vger.kernel.org, devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Brian Norris , Douglas Anderson Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 31, 2018 at 1:34 PM, Matthias Kaehlcke wrote: > Hi Rob, > > On Thu, May 31, 2018 at 11:31:59AM -0500, Rob Herring wrote: >> On Fri, May 25, 2018 at 01:30:42PM -0700, Matthias Kaehlcke wrote: >> >> Commit msg? > > Will add some more info in the next revision. > >> > Signed-off-by: Matthias Kaehlcke >> > --- >> > .../devicetree/bindings/misc/throttler.txt | 41 +++++++++++++++++++ >> > 1 file changed, 41 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/misc/throttler.txt >> > >> > diff --git a/Documentation/devicetree/bindings/misc/throttler.txt b/Documentation/devicetree/bindings/misc/throttler.txt >> > new file mode 100644 >> > index 000000000000..92f13e94451a >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/misc/throttler.txt >> > @@ -0,0 +1,41 @@ >> > +Throttler driver >> > + >> > +The Throttler is used for non-thermal throttling of system components like >> > +CPUs or devfreq devices. >> >> This all looks very Linux specific and not a h/w device. Perhaps you can >> add hint properties to OPP tables as to what entries can be used for >> throttling, but otherwise this doesn't belong in DT. > > My idea is to allow multiple throttlers, which might operate on > different throttling devices or use different OPPs for the same > device. To support this a simple boolean hint that the OPP can be used > for throttling would not be sufficient. > > What should work is a property with an array of phandles of the > throttlers that use a given OPP. > > AFAIK it is currently not possible to enumerate the devfreq devices in > the system, so besides the info in the OPPs the throttler itself would > still need a phandle to the devfreq device(s) it uses. Why don't you fix that OS problem instead of working around it in DT? > > I envision something like this: > > gpu_opp_table: opp-table2 { > compatible = "operating-points-v2"; > > opp00 { > opp-hz = /bits/ 64 <200000000>; > opp-microvolt = <800000>; > }; > opp01 { > opp-hz = /bits/ 64 <297000000>; > opp-microvolt = <800000>; > opp-throttlers = <&cros_ec_throttler>; > }; > ... > }; > > cros_ec_throttler: cros-ec-throttler { > compatible = "google,cros-ec-throttler"; Is this an actual h/w device? > > devfreq-devices = <&gpu>; > }; > > Would this be acceptable? > > Thanks > > Matthias