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s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VSaFeBdX4kWGJjrK0LDIdAG7HMHyEVXfRCzRhlCm2Vc=; b=TC7oj0NrGAVcqBPmLdGYRqlfPBuHyci/eE4VaLp8Wny5A9lq4PuqSiP10p8JjGxDw4 LZ8iDClwboWoVxCOpHSApKUk5RPi3BJsHIKFu2EsWsnS1RkDHEDsxQRyIbmy2M6mtmBi zO5eR/UIXcAT+oRjv6LIas8x6i7YdxwhToiOf3YDZqFaZTUbKPiwqMbQUaZKpytW9ys6 /5KE6KCcbEGiBh7C3Kn2ioP2CsOzP+wkcgtAkEpz9nUvwzUIpGNZXIfuq3fbIoODqE2M nMgWDU6s3hQOufL/qiou9fNbFylrmyq+yk1tIYG/RAXlqMGqhVt+RoQKLJ3qcPmUNbWO MaEg== X-Gm-Message-State: AOAM532BL2dJxgaTiCa5U60zRdnoI3e1IzUauNkNDAnlIJD0MLYg0YBQ t6mVytRS2Mn+jTntQKMbiYRdgzC+fQ2iceyd61FRAA== X-Google-Smtp-Source: ABdhPJyCu5OoKXB/ZnU0BhDnI9FQ/nriFA8C9gxuFpc66zGzEUSQ7NZWEdQGpN5i65y/ydiL4YG1C5HABdRFQK6zhTY= X-Received: by 2002:a67:3212:: with SMTP id y18mr16683598vsy.19.1629464287428; Fri, 20 Aug 2021 05:58:07 -0700 (PDT) MIME-Version: 1.0 References: <080469b3-612b-3a34-86e5-7037a64de2fe@gmail.com> <20210818055849.ybfajzu75ecpdrbn@vireshk-i7> <20210818062723.dqamssfkf7lf7cf7@vireshk-i7> <20210818091417.dvlnsxlgybdsn76x@vireshk-i7> <20210819061617.r4kuqxafjstrv3kt@vireshk-i7> <20210820051843.5mueqpnjbqt3zdzc@vireshk-i7> In-Reply-To: <20210820051843.5mueqpnjbqt3zdzc@vireshk-i7> From: Ulf Hansson Date: Fri, 20 Aug 2021 14:57:31 +0200 Message-ID: Subject: Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper To: Viresh Kumar , Dmitry Osipenko Cc: Thierry Reding , Jonathan Hunter , Viresh Kumar , Stephen Boyd , Peter De Schrijver , Mikko Perttunen , Peter Chen , Mark Brown , Lee Jones , =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= , Nishanth Menon , Vignesh Raghavendra , Richard Weinberger , Miquel Raynal , Lucas Stach , Stefan Agner , Adrian Hunter , Mauro Carvalho Chehab , Rob Herring , Michael Turquette , Linux Kernel Mailing List , linux-tegra , Linux PM , Linux USB List , linux-staging@lists.linux.dev, linux-spi@vger.kernel.org, linux-pwm@vger.kernel.org, linux-mtd@lists.infradead.org, linux-mmc , Linux Media Mailing List , dri-devel , DTML , linux-clk X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210820_055808_983722_0554396E X-CRM114-Status: GOOD ( 39.89 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Fri, 20 Aug 2021 at 07:18, Viresh Kumar wrote: > > On 19-08-21, 16:55, Ulf Hansson wrote: > > Right, that sounds reasonable. > > > > We already have pm_genpd_opp_to_performance_state() which translates > > an OPP to a performance state. This function invokes the > > ->opp_to_performance_state() for a genpd. Maybe we need to allow a > > genpd to not have ->opp_to_performance_state() callback assigned > > though, but continue up in the hierarchy to see if the parent has the > > callback assigned, to make this work for Tegra? > > > > Perhaps we should add an API dev_pm_genpd_opp_to_performance_state(), > > allowing us to pass the device instead of the genpd. But that's a > > minor thing. > > I am not concerned a lot about how it gets implemented, and am not > sure as well, as I haven't looked into these details since sometime. > Any reasonable thing will be accepted, as simple as that. > > > Finally, the precondition to use the above, is to first get a handle > > to an OPP table. This is where I am struggling to find a generic > > solution, because I guess that would be platform or even consumer > > driver specific for how to do this. And at what point should we do > > this? > > Hmm, I am not very clear with the whole picture at this point of time. > > Dmitry, can you try to frame a sequence of events/calls/etc that will > define what kind of devices we are looking at here, and how this can > be made to work ? > > > > > Viresh, please take a look at what I did in [1]. Maybe it could be done > > > > in another way. > > > > > > I looked into this and looked like too much trouble. The > > > implementation needs to be simple. I am not sure I understand all the > > > problems you faced while doing that, would be better to start with a > > > simpler implementation of get_performance_state() kind of API for > > > genpd, after the domain is attached and its OPP table is initialized. > > > > > > Note, that the OPP table isn't required to be fully initialized for > > > the device at this point, we can parse the DT as well if needed be. > > > > Sure, but as I indicated above, you need some kind of input data to > > figure out what OPP table to pick, before you can translate that into > > a performance state. Is that always the clock rate, for example? > > Eventually it can be clock, bandwidth, or pstate of anther genpd, not > sure what all we are looking for now. It should be just clock right > now as far as I can imagine :) > > > Perhaps, we should start with adding a dev_pm_opp_get_from_rate() or > > what do you think? Do you have other suggestions? > > We already have similar APIs, so that won't be a problem. We also have > a mechanism inside the OPP core, frequency based, which is used to > guess the current OPP. Maybe we can enhance and use that directly > here. After reading the last reply from Dmitry, I am starting to think that the problem he is facing can be described and solved in a much easier way. If I am correct, it looks like we don't need to add APIs to get OPPs for a clock rate or set initial performance state values according to the HW in genpd. See my other response to Dmitry, let's see where that leads us. Kind regards Uffe ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/