From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for power-domains Date: Wed, 19 Apr 2017 14:58:00 +0100 Message-ID: <9dee7c0d-e5f4-9fcd-3c92-bf7ec9d43a3b@arm.com> References: <0a7146f9-72f1-317c-3aab-770a72462968@arm.com> <20170413053736.GM5910@vireshk-i7> <3adbef6a-7b43-528f-e88f-c2121d30a5d3@arm.com> <20170417052758.GF28191@vireshk-i7> <95aa4b97-4e1a-13bb-f4d8-982b778012ba@arm.com> <20170419114740.GD5436@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170419114740.GD5436@vireshk-i7> Sender: linux-pm-owner@vger.kernel.org To: Viresh Kumar Cc: Sudeep Holla , Rafael Wysocki , ulf.hansson@linaro.org, Kevin Hilman , Viresh Kumar , Nishanth Menon , Stephen Boyd , linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Guittot , robh+dt@kernel.org, lina.iyer@linaro.org, rnayak@codeaurora.org, devicetree@vger.kernel.org List-Id: devicetree@vger.kernel.org On 19/04/17 12:47, Viresh Kumar wrote: > On 18-04-17, 17:01, Sudeep Holla wrote: >> Understood. I would incline towards reusing regulators we that's what is > > It can be just a regulator, but it can be anything else as well. That > entity may have its own clock/volt/current tunables, etc. > Agreed. >> changed behind the scene. Calling this operating performance point >> is misleading and doesn't align well with existing specs/features. > > Yeah, but there are no voltage levels available here and that doesn't > fit as a regulator then. > We can't dismiss just based on that. We do have systems where performance index is mapped to clocks though it may not be 1:1 mapping. I am not disagreeing here, just trying to understand it better. >> Understood. We have exactly same thing with SCPI but it controls both >> frequency and voltage referred as operating points. In general, this OPP >> terminology is used in SCPI/ACPI/SCMI specifications as both frequency >> and voltage control. I am bit worried that this binding might introduce >> confusions on the definitions. But it can be reworded/renamed easily if >> required. > > Yeah, so far we have been looking at OPPs as freq-voltage pairs ONLY > and that is changing. I am not sure if it going in the wrong > direction really. Without frequency also it is an operating point for > the domain. Isn't it? > Yes, I completely agree. I am not saying the direction is wrong. I am saying it's confusing and binding needs to be more clear. On the contrary(playing devil's advocate here), we can treat all existing regulators alone as OPP then if you strip the voltages and treat it as abstract number. So if the firmware handles more than just regulators, I agree. At the same time, I would have preferred firmware to even abstract the frequency like ACPI CPPC. It would be good to get more information on what exactly that firmware handles. I am just more cautious here since we are designing generic bindings and changing generic code, we need to understand what that firmware supports and how it may evolve(so that we can maintain DT compatibility) I did a brief check and wanted to check if this is SMD/RPM regulators ? -- Regards, Sudeep