linux-kernel - Re: [PATCH] cpufreq: tegra186: Fix get frequency callback

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Date:   Mon, 16 Nov 2020 15:55:23 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>
CC:     Thierry Reding <thierry.reding@...il.com>,
        Sumit Gupta <sumitg@...dia.com>, <linux-pm@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: tegra186: Fix get frequency callback

Hi Rafael,

On 04/11/2020 09:33, Viresh Kumar wrote:
> On 03-11-20, 11:55, Jon Hunter wrote:
>> Commit b89c01c96051 ("cpufreq: tegra186: Fix initial frequency")
>> implemented the CPUFREQ 'get' callback to determine the current
>> operating frequency for each CPU. This implementation used a simple
>> looked up to determine the current operating frequency. The problem
>> with this is that frequency table for different Tegra186 devices may
>> vary and so the default boot frequency for Tegra186 device may or may
>> not be present in the frequency table. If the default boot frequency is
>> not present in the frequency table, this causes the function
>> tegra186_cpufreq_get() to return 0 and in turn causes cpufreq_online()
>> to fail which prevents CPUFREQ from working.
>>
>> Fix this by always calculating the CPU frequency based upon the current
>> 'ndiv' setting for the CPU. Note that the CPU frequency for Tegra186 is
>> calculated by reading the current 'ndiv' setting, multiplying by the
>> CPU reference clock and dividing by a constant divisor.
>>
>> Fixes: b89c01c96051 ("cpufreq: tegra186: Fix initial frequency")
>>
>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>> ---
>>  drivers/cpufreq/tegra186-cpufreq.c | 33 +++++++++++++++++++-----------
>>  1 file changed, 21 insertions(+), 12 deletions(-)
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> Rafael: This needs to go in the next rc and so I am not applying it
> in my tree as this is the only fix I have for now.


Are you able to pick this up for v5.10 fixes?

Thanks
Jon

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