From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver Date: Wed, 4 Dec 2019 16:57:53 +0300 Message-ID: <0b634341-ea2b-e9cd-4986-dc9a01c839bb@gmail.com> References: <1575394348-17649-1-git-send-email-sumitg@nvidia.com> <1575394348-17649-2-git-send-email-sumitg@nvidia.com> <20191204054043.o4ff7pnqec3fwdgu@vireshk-i7> <7347caa6-43a3-f761-de83-481b45f7b22a@nvidia.com> <20191204112749.jkwlyteal4hfvnhb@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20191204112749.jkwlyteal4hfvnhb@vireshk-i7> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Viresh Kumar , sumitg Cc: rjw@rjwysocki.net, catalin.marinas@arm.com, will@kernel.org, thierry.reding@gmail.com, jonathanh@nvidia.com, talho@nvidia.com, linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, bbasu@nvidia.com, mperttunen@nvidia.com List-Id: linux-tegra@vger.kernel.org 04.12.2019 14:27, Viresh Kumar пишет: > On 04-12-19, 16:25, sumitg wrote: >> In T194, CCPLEX doesn't have access to set clocks and the >> >> clk_{get|set}_rate() functions set clocks by hook to BPMP R5. >> >> CPU freq can be directly set by CCPLEX using MSR(NVFREQ_REQ_EL1). >> >> As DVFS run's on BPMP, another MSR (NVFREQ_FEEDBACK_EL1) is >> >> used to read the counters and calculate "actual" cpu freq at CCPLEX. >> >> So, "cpuinfo_cur_freq" node gives the actual cpu frequency and not >> >> given by node "scaling_cur_freq". > > Right, but why can't this be hidden in the CPU's clk driver instead, > so cpufreq driver can just do clk_get_rate() and clk_set_rate() ? What about to make use of dev_pm_opp_register_set_opp_helper()? >>> - populating cpufreq table, you can probably add OPPs instead using >>> the same mechanism >> >> We are reading available frequencies from BPMP to populate >> >> cpufreq table and not using static opp table. > > Right and lot of other platforms read it from firmware (I believe BBMP > is a firmware here), and create OPPs at runtime. Look at this for > example: > > drivers/cpufreq/qcom-cpufreq-hw.c > > and search for dev_pm_opp_add(). >