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Date: Wed, 9 Nov 2022 13:19:08 +0530 From: Manivannan Sadhasivam <mani@...nel.org> To: Sudeep Holla <sudeep.holla@....com> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, andersson@...nel.org, viresh.kumar@...aro.org, krzysztof.kozlowski+dt@...aro.org, rafael@...nel.org, robh+dt@...nel.org, johan@...nel.org, devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org Subject: Re: [PATCH v5 3/3] cpufreq: qcom-hw: Add CPU clock provider support On Tue, Nov 08, 2022 at 03:57:17PM +0000, Sudeep Holla wrote: > On Tue, Nov 08, 2022 at 09:10:37PM +0530, Manivannan Sadhasivam wrote: > > Qcom CPUFreq hardware (EPSS/OSM) controls clock and voltage to the CPU > > cores. But this relationship is not represented with the clk framework > > so far. > > > > So, let's make the qcom-cpufreq-hw driver a clock provider. This makes the > > clock producer/consumer relationship cleaner and is also useful for CPU > > related frameworks like OPP to know the frequency at which the CPUs are > > running. > > > > The clock frequency provided by the driver is for each frequency domain. > > We cannot get the frequency of each CPU core because, not all platforms > > support per-core DCVS feature. > > > > Also the frequency supplied by the driver is the actual frequency that > > comes out of the EPSS/OSM block after the DCVS operation. This frequency is > > not same as what the CPUFreq framework has set but it is the one that gets > > supplied to the CPUs after throttling by LMh. > > > > OK now I see more info here. How different is this value from the one > returned by qcom_cpufreq_hw_get() ? > qcom_cpufreq_hw_get() returns the frequency that got programmed by the cpufreq core. But that frequency is not necessarily the one that gets delivered to the CPU cores because the EPSS/OSM hardware block may vary the frequency after the DCVS operation. So this frequency is the final one that gets delivered to the CPU cores. Thanks, Mani > -- > Regards, > Sudeep -- மணிவண்ணன் சதாசிவம்
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