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

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Message-ID: <20201117043600.bqzr3zmw6n7vj3fj@vireshk-i7>
Date:   Tue, 17 Nov 2020 10:06:00 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        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

On 16-11-20, 15:55, Jon Hunter wrote:
> 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?

Applied to my tree now, will send a PULL request soon.

-- 
viresh