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[46.138.85.91]) by smtp.googlemail.com with ESMTPSA id f1sm381628lfs.44.2021.08.17.21.29.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Aug 2021 21:29:39 -0700 (PDT) Subject: Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper From: Dmitry Osipenko 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> Message-ID: <6df0ed60-e497-0af2-09b6-a9d82f502f17@gmail.com> Date: Wed, 18 Aug 2021 07:29:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <5b2a80c1-9743-e633-6257-ede94c8a274c@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 18.08.2021 07:12, Dmitry Osipenko пишет: > 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. > Notice that we use GENPD here. GENPD core takes care of storing PD's performance state (voltage in case of Tegra) and dropping it to 0 after rpm-suspend, GENPD core also restores the state before rpm-resume.