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[46.138.85.91]) by smtp.googlemail.com with ESMTPSA id s27sm379103lfs.279.2021.08.17.21.37.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Aug 2021 21:37:47 -0700 (PDT) Subject: Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper To: Viresh Kumar Cc: Thierry Reding , Jonathan Hunter , Ulf Hansson , Viresh Kumar , Stephen Boyd , Peter De Schrijver , Mikko Perttunen , Peter Chen , Mark Brown , Lee Jones , =?UTF-8?Q?Uwe_Kleine-K=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@vger.kernel.org, linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org, linux-usb@vger.kernel.org, linux-staging@lists.linux.dev, linux-spi@vger.kernel.org, linux-pwm@vger.kernel.org, linux-mtd@lists.infradead.org, linux-mmc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org References: <20210817012754.8710-1-digetx@gmail.com> <20210817012754.8710-2-digetx@gmail.com> <20210817075515.vyyv7z37e6jcrhsl@vireshk-i7> <710261d9-7ae3-5155-c0a2-f8aed2408d0b@gmail.com> <20210818035533.ieqkexltfvvf2p4n@vireshk-i7> <5b2a80c1-9743-e633-6257-ede94c8a274c@gmail.com> <20210818043131.7klajx6drvvkftoc@vireshk-i7> From: Dmitry Osipenko Message-ID: Date: Wed, 18 Aug 2021 07:37:46 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210818043131.7klajx6drvvkftoc@vireshk-i7> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org 18.08.2021 07:31, Viresh Kumar пишет: > On 18-08-21, 07:12, Dmitry Osipenko wrote: >> 18.08.2021 06:55, Viresh Kumar пишет: >>> On 17-08-21, 18:49, Dmitry Osipenko wrote: >>>> 17.08.2021 10:55, Viresh Kumar пишет: >>>> ... >>>>>> +int dev_pm_opp_sync(struct device *dev) >>>>>> +{ >>>>>> + struct opp_table *opp_table; >>>>>> + struct dev_pm_opp *opp; >>>>>> + int ret = 0; >>>>>> + >>>>>> + /* Device may not have OPP table */ >>>>>> + opp_table = _find_opp_table(dev); >>>>>> + if (IS_ERR(opp_table)) >>>>>> + return 0; >>>>>> + >>>>>> + if (!_get_opp_count(opp_table)) >>>>>> + goto put_table; >>>>>> + >>>>>> + opp = _find_current_opp(dev, opp_table); >>>>>> + ret = _set_opp(dev, opp_table, opp, opp->rate); >>>>> >>>>> And I am not sure how this will end up working, since new OPP will be >>>>> equal to old one. Since I see you call this from resume() at many >>>>> places. >>>> >>>> Initially OPP table is "uninitialized" and opp_table->enabled=false, >>>> hence the first sync always works even if OPP is equal to old one. Once >>>> OPP has been synced, all further syncs are NO-OPs, hence it doesn't >>>> matter how many times syncing is called. >>>> >>>> https://elixir.bootlin.com/linux/v5.14-rc6/source/drivers/opp/core.c#L1012 >>> >>> Right, but how will this work from Resume ? Won't that be a no-op ? >> >> The first resume initializes the OPP state on sync, all further syncs on >> resume are no-ops. > > But the OPPs should already be initialized as someone must have called > opp-set-rate earlier ? Why do this from resume and not probe ? This will set voltage level without having an actively used hardware. Take a 3d driver for example, if you set the rate on probe and rpm-resume will never be called, then the voltage will be set high, while hardware is kept suspended if userspace will never wake it up by executing a 3d job.