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[109.252.192.83]) by smtp.googlemail.com with ESMTPSA id 144sm176642ljj.48.2020.11.05.07.22.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Nov 2020 07:22:10 -0800 (PST) Subject: Re: [PATCH v1 00/30] Introduce core voltage scaling for NVIDIA Tegra20/30 SoCs To: Ulf Hansson , Viresh Kumar Cc: Thierry Reding , Jonathan Hunter , Alan Stern , Peter Chen , Mark Brown , Liam Girdwood , Adrian Hunter , Krzysztof Kozlowski , Greg Kroah-Hartman , Lee Jones , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Mauro Carvalho Chehab , Rob Herring , Marek Szyprowski , Peter Geis , Nicolas Chauvet , linux-samsung-soc , driverdevel , Linux USB List , linux-pwm@vger.kernel.org, "linux-mmc@vger.kernel.org" , Linux Kernel Mailing List , DTML , dri-devel , Linux Media Mailing List , linux-tegra References: <20201104234427.26477-1-digetx@gmail.com> From: Dmitry Osipenko Message-ID: Date: Thu, 5 Nov 2020 18:22:09 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 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: devicetree@vger.kernel.org 05.11.2020 12:45, Ulf Hansson пишет: ... > I need some more time to review this, but just a quick check found a > few potential issues... Thank you for starting the review! I'm pretty sure it will take a couple revisions until all the questions will be resolved :) > The "core-supply", that you specify as a regulator for each > controller's device node, is not the way we describe power domains. > Instead, it seems like you should register a power-domain provider > (with the help of genpd) and implement the ->set_performance_state() > callback for it. Each device node should then be hooked up to this > power-domain, rather than to a "core-supply". For DT bindings, please > have a look at Documentation/devicetree/bindings/power/power-domain.yaml > and Documentation/devicetree/bindings/power/power_domain.txt. > > In regards to the "sync state" problem (preventing to change > performance states until all consumers have been attached), this can > then be managed by the genpd provider driver instead. I'll need to take a closer look at GENPD, thank you for the suggestion. Sounds like a software GENPD driver which manages clocks and voltages could be a good idea, but it also could be an unnecessary over-engineering. Let's see..