linux-kernel - Re: [PATCH v5] Force cppc_cpufreq to report values in KHz to fix user space reporting

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Message-ID: <3ab83afa-1c91-4dcc-9206-a7a6dc3cfe83@redhat.com>
Date:	Mon, 1 Aug 2016 14:07:25 -0600
From:	Al Stone <ahs3@...hat.com>
To:	viresh.kumar@...aro.org, ashwin.chaugule@...aro.org,
	rjw@...ysocki.net
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Prashanth Prakash <pprakash@...eaurora.org>
Subject: Re: [PATCH v5] Force cppc_cpufreq to report values in KHz to fix user
 space reporting

On 07/20/2016 03:10 PM, Al Stone wrote:
> When CPPC is being used by ACPI on arm64, user space tools such as
> cpupower report CPU frequency values from sysfs that are incorrect.
> 
> What the driver was doing was reporting the values given by ACPI tables
> in whatever scale was used to provide them.  However, the ACPI spec
> defines the CPPC values as unitless abstract numbers.  Internal kernel
> structures such as struct perf_cap, in contrast, expect these values
> to be in KHz.  When these struct values get reported via sysfs, the
> user space tools also assume they are in KHz, causing them to report
> incorrect values (for example, reporting a CPU frequency of 1MHz when
> it should be 1.8GHz).
> [snip...]

Ping?  If anyone has sent comments, I have not received them.

Thanks in advance for the time and effort.  I know merge window can be
a very busy time.

-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@...hat.com
-----------------------------------