From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH v9 2/8] dt-bindings: Introduce interconnect binding Date: Wed, 3 Oct 2018 10:33:46 +0100 Message-ID: <20181003093346.GA12570@e107155-lin> References: <20180831140151.13972-1-georgi.djakov@linaro.org> <20180831140151.13972-3-georgi.djakov@linaro.org> <20180925180215.GA12435@bogus> <20180926144830.GB25838@e107155-lin> <20181002111758.GC1086@e107155-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Saravana Kannan Cc: Georgi Djakov , Rob Herring , linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, rjw@rjwysocki.net, mturquette@baylibre.com, khilman@baylibre.com, vincent.guittot@linaro.org, bjorn.andersson@linaro.org, amit.kucheria@linaro.org, seansw@qti.qualcomm.com, daidavid1@codeaurora.org, evgreen@chromium.org, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, abailon@baylibre.com, maxime.ripard@bootlin.com, arnd@arndb.de, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, Sudeep Holla List-Id: devicetree@vger.kernel.org On Tue, Oct 02, 2018 at 11:56:56AM -0700, Saravana Kannan wrote: > > On 10/02/2018 04:17 AM, Sudeep Holla wrote: [...] > > Yes, I do understand I have made the same point multiple time and it's > > intentional. We need to get the fragmented f/w support story fixed. > > Different ARM vendors are doing different things in f/w and ARM sees the > > same fragmentation story as before. We have come up with new specification > > and my annoying multiple emails are just to constantly remind the same. > > > > I do understand we have existing implementations to consider, but fixing > > the functionality in arbitrary way is not a good design and it better > > to get them fixed for future. > > I believe the fragmentation you are referring to is  in the > interface/communication protocol. I see the benefit of standardizing that as > long as the standard actually turns out to be good. But that's completely > separate from what the FW can/can't do. Asking to standardize what the FW > can/can't do doesn't seem realistic as each chip vendor will have different > priorities - power, performance, cost, chip area, etc. It's the conflation > of these separate topics that doesn't help IMHO. I agree on interface/communication protocol fragmentation and firmware can implement whatever the vendor wish. What I was also referring was the mix-n-match approach which should be avoided. e.g. Device A and B's PM is managed completely by firmware using OSPM hints Suppose Device X's PM is dependent on Device A and B, in which case it's simpler and cleaner to leave Device X PM to firmware. Reading the state of A and B and using that as hint for X is just overhead which firmware can manage better. That was my main concern here: A=CPU and B=some other device and X is inter-connect to which A and B are connected. If CPU OPPs are obtained from f/w and this inter-connect from DT, mapping then is a mess and that's what I was concerned. I am sorry if that's not the scenario here, I may have mistaken then. -- Regards, Sudeep