linux-kernel - Re: [Patch 1/6] cpufreq: use correct unit when verify cur freq

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Date:   Tue, 18 Apr 2023 14:57:05 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sumit Gupta <sumitg@...dia.com>
Cc:     viresh.kumar@...aro.org, rafael@...nel.org,
        ionela.voinescu@....com, mark.rutland@....com,
        sudeep.holla@....com, lpieralisi@...nel.org,
        catalin.marinas@....com, will@...nel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, treding@...dia.com,
        jonathanh@...dia.com, vsethi@...dia.com, sdonthineni@...dia.com,
        sanjayc@...dia.com, ksitaraman@...dia.com, bbasu@...dia.com
Subject: Re: [Patch 1/6] cpufreq: use correct unit when verify cur freq

On Tue, Apr 18, 2023 at 1:35 PM Sumit Gupta <sumitg@...dia.com> wrote:
>
> From: Sanjay Chandrashekara <sanjayc@...dia.com>
>
> cpufreq_verify_current_freq checks if the frequency returned by
> the hardware has a slight delta with the valid frequency value
> last set and returns "policy->cur" if the delta is within "1 MHz".
> In the comparison, "policy->cur" is in "kHz" but it's compared
> against HZ_PER_MHZ. So, the comparison range becomes "1 GHz".
> Fix this by comparing against KHZ_PER_MHZ instead of HZ_PER_MHZ.
>
> Fixes: f55ae08c8987 ("cpufreq: Avoid unnecessary frequency updates due to mismatch")
> Signed-off-by: Sanjay Chandrashekara <sanjayc@...dia.com>
> [ sumit gupta: Commit message update ]
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/cpufreq/cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 8b0509f89f1b..6b52ebe5a890 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1732,7 +1732,7 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b
>                  * MHz. In such cases it is better to avoid getting into
>                  * unnecessary frequency updates.
>                  */
> -               if (abs(policy->cur - new_freq) < HZ_PER_MHZ)
> +               if (abs(policy->cur - new_freq) < KHZ_PER_MHZ)
>                         return policy->cur;
>
>                 cpufreq_out_of_sync(policy, new_freq);
> --

So this is a fix that can be applied separately from the rest of the
series, isn't it?