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

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Message-ID: <8522b877-3f6f-8225-4a9f-512d15b3d477@nvidia.com>
Date:   Sat, 2 Sep 2023 01:23:12 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     Jon Hunter <jonathanh@...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>,
        "Sumit Gupta" <sumitg@...dia.com>
Subject: Re: [Patch v2 2/2] cpufreq: tegra194: use refclk delta based loop
 instead of udelay



On 01/09/23 23:29, Jon Hunter wrote:
> 
> 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
> 

This patch is newly added in v2.

Thank you,
Sumit Gupta