linux-kernel - Re: [PATCH v5 0/2] add SW BOOST support for CPPC

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Date:   Tue, 2 Jun 2020 10:46:09 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc:     rjw@...ysocki.net, Souvik.Chakravarty@....com,
        Thanu.Rangarajan@....com, Sudeep.Holla@....com,
        guohanjun@...wei.com, john.garry@...wei.com,
        jonathan.cameron@...wei.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/2] add SW BOOST support for CPPC

On 30-05-20, 10:08, Xiongfeng Wang wrote:
> ACPI spec 6.2 section 8.4.7.1 provide the following two CPC registers.
> 
> "Highest performance is the absolute maximum performance an individual
> processor may reach, assuming ideal conditions. This performance level
> may not be sustainable for long durations, and may only be achievable if
> other platform components are in a specific state; for example, it may
> require other processors be in an idle state.
> 
> Nominal Performance is the maximum sustained performance level of the
> processor, assuming ideal operating conditions. In absence of an
> external constraint (power, thermal, etc.) this is the performance level
> the platform is expected to be able to maintain continuously. All
> processors are expected to be able to sustain their nominal performance
> state simultaneously."
> 
> We can use Highest Performance as the max performance in boost mode and
> Nomial Performance as the max performance in non-boost mode. If the
> Highest Performance is greater than the Nominal Performance, we assume
> SW BOOST is supported.
> 
> Changelog:
> 
> v4 -> v5:
> 	add 'cpu_hotplug_lock' before calling '.set_boost'
> v3 -> v4:
> 	run 'boost_set_msr_each' for each CPU in the policy rather than
> 	each CPU in the system for 'acpi-cpufreq'
> 	add 'Suggested-by'
> 
> Xiongfeng Wang (2):
>   cpufreq: change '.set_boost' to act on only one policy
>   CPPC: add support for SW BOOST
> 
>  drivers/cpufreq/acpi-cpufreq.c | 14 ++++++-----
>  drivers/cpufreq/cppc_cpufreq.c | 39 +++++++++++++++++++++++++++--
>  drivers/cpufreq/cpufreq.c      | 57 +++++++++++++++++++++++-------------------
>  include/linux/cpufreq.h        |  2 +-
>  4 files changed, 77 insertions(+), 35 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh