linux-kernel - Re: [Patch v2 2/2] cpufreq: tegra194: use refclk delta based loop instead of udelay

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Date:   Fri, 1 Sep 2023 18:59:24 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Sumit Gupta <sumitg@...dia.com>, rafael@...nel.org,
        viresh.kumar@...aro.org, linux-pm@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     treding@...dia.com, bbasu@...dia.com, amiettinen@...dia.com
Subject: Re: [Patch v2 2/2] cpufreq: tegra194: use refclk delta based loop
 instead of udelay


On 01/09/2023 17:41, Sumit Gupta wrote:
> Use reference clock count based loop instead of "udelay()" for
> sampling of counters to improve the accuracy of re-generated CPU
> frequency. "udelay()" internally calls "WFE" which stops the
> counters and results in bigger delta between the last set freq
> and the re-generated value from counters. The counter sampling
> window used in loop is the minimum number of reference clock
> cycles which is known to give a stable value of CPU frequency.
> The change also helps to reduce the sampling window from "500us"
> to "<50us".
> 
> Suggested-by: Antti Miettinen <amiettinen@...dia.com>
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---

Same here.

Jon

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