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Date:   Mon, 31 Jul 2023 15:02:47 -0700
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Subject: Re: [PATCH v3 2/2] cpufreq: add virtual-cpufreq driver
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To:     David Dai <davidai@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Saravana Kannan <saravanak@google.com>
Cc:     Quentin Perret <qperret@google.com>,
        Masami Hiramatsu <mhiramat@google.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Pavan Kondeti <quic_pkondeti@quicinc.com>,
        Gupta Pankaj <pankaj.gupta@amd.com>,
        Mel Gorman <mgorman@suse.de>, kernel-team@android.com,
        linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230731174613.4133167-1-davidai@google.com>
 <20230731174613.4133167-3-davidai@google.com>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <20230731174613.4133167-3-davidai@google.com>
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On 7/31/23 10:46, David Dai wrote:
> diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> index f429b9b37b76..3977ca796747 100644
> --- a/drivers/cpufreq/Kconfig
> +++ b/drivers/cpufreq/Kconfig
> @@ -217,6 +217,21 @@ config CPUFREQ_DT
>  
>  	  If in doubt, say N.
>  
> +config CPUFREQ_VIRT
> +        tristate "Virtual cpufreq driver"
> +	depends on OF
> +	select PM_OPP
> +        help

The 4 lines above should be indented with one tab (not 8 spaces).

> +	  This adds a virtualized cpufreq driver for guest kernels that
> +	  read/writes to a MMIO region for a virtualized cpufreq device to

	  reads/writes to an MMIO region

> +	  communicate with the host. It sends frequency updates to the host
> +	  which gets used as a hint to schedule vCPU threads and select CPU
> +	  frequency. If a VM does not support a virtualized FIE such as AMUs,
> +	  it updates the frequency scaling factor by polling host CPU frequency
> +	  to enable accurate Per-Entity Load Tracking for tasks running in the guest.
> +
> +	  If in doubt, say N.

-- 
~Randy