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[79.139.163.57]) by smtp.googlemail.com with ESMTPSA id s30sm2577705lfb.90.2021.10.06.14.25.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 06 Oct 2021 14:25:06 -0700 (PDT) Subject: Re: [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain To: Ulf Hansson Cc: Thierry Reding , Jonathan Hunter , Viresh Kumar , Stephen Boyd , Peter De Schrijver , Mikko Perttunen , Peter Chen , Lee Jones , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Nishanth Menon , Adrian Hunter , Michael Turquette , Linux Kernel Mailing List , linux-tegra , Linux PM , Linux USB List , linux-staging@lists.linux.dev, linux-pwm@vger.kernel.org, linux-mmc , dri-devel , DTML , linux-clk , Mark Brown , Vignesh Raghavendra , Richard Weinberger , Miquel Raynal , Lucas Stach , Stefan Agner , Mauro Carvalho Chehab , David Heidelberg References: <20210926224058.1252-1-digetx@gmail.com> <20210926224058.1252-7-digetx@gmail.com> <24101cd6-d3f5-1e74-db39-145ecd30418b@gmail.com> <4bdba8a2-4b9b-ed7d-e6ca-9218d8200a85@gmail.com> From: Dmitry Osipenko Message-ID: <35714b9d-d855-1ad3-241b-f97859f8c97b@gmail.com> Date: Thu, 7 Oct 2021 00:25:05 +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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 06.10.2021 15:38, Ulf Hansson пишет: >> I'm also wondering if we could add some 'was_enabled' flag to GENPDs, >> setting it by genpd_suspend_noirq() for the enabled domains, and then >> powering-on GENPDs from genpd_resume_noirq() only if they were in the >> enabled state during genpd_suspend_noirq() time. It actually puzzled me >> for a quite long time why GENPD core enables domains unconditionally >> during early resume. This should solve a part of the problem and it >> makes suspend/resume a bit safer because there is a smaller chance to >> crash hardware during suspend, at least it's easier to debug. > Just because the PM domain was already off at genpd_suspend_noirq(), > doesn't mean that it can stay powered off at genpd_resume_noirq(). At > least as is today. > > The main reason why genpd_resume_noirq() powers on the PM domain, is > because it's not possible for the consumer drivers to rely on runtime > PM to do it (because runtime PM has been disabled by the PM core). At least Tegra doesn't need to have domains force-resumed. This should be a platform-specific behaviour. We may add a new flag for that, I suppose. I'll try to keep this in mind for a future improvement. Thank you for the clarification.