linux-kernel - Re: [PATCH] cpufreq: Improve code around unlisted freq check

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Date:   Fri, 16 Oct 2020 16:21:25 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Sumit Gupta <sumitg@...dia.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: Improve code around unlisted freq check

On Tue, Oct 13, 2020 at 7:12 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> The cpufreq core checks if the frequency programmed by the bootloaders
> is not listed in the freq table and programs one from the table in such
> a case. This is done only if the driver has set the
> CPUFREQ_NEED_INITIAL_FREQ_CHECK flag.
>
> Currently we print two separate messages, with almost the same content,
> and do this with a pr_warn() which may be a bit too much as the driver
> only asked us to check this as it expected this to be the case. Lower
> down the severity of the print message by switching to pr_info() instead
> and print a single message only.
>
> Reported-by: Sumit Gupta <sumitg@...dia.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 2ea245a6c0c0..99864afac272 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1461,14 +1461,13 @@ static int cpufreq_online(unsigned int cpu)
>          */
>         if ((cpufreq_driver->flags & CPUFREQ_NEED_INITIAL_FREQ_CHECK)
>             && has_target()) {
> +               unsigned int old_freq = policy->cur;
> +
>                 /* Are we running at unknown frequency ? */
> -               ret = cpufreq_frequency_table_get_index(policy, policy->cur);
> +               ret = cpufreq_frequency_table_get_index(policy, old_freq);
>                 if (ret == -EINVAL) {
> -                       /* Warn user and fix it */
> -                       pr_warn("%s: CPU%d: Running at unlisted freq: %u KHz\n",
> -                               __func__, policy->cpu, policy->cur);
> -                       ret = __cpufreq_driver_target(policy, policy->cur - 1,
> -                               CPUFREQ_RELATION_L);
> +                       ret = __cpufreq_driver_target(policy, old_freq - 1,
> +                                                     CPUFREQ_RELATION_L);
>
>                         /*
>                          * Reaching here after boot in a few seconds may not
> @@ -1476,8 +1475,8 @@ static int cpufreq_online(unsigned int cpu)
>                          * frequency for longer duration. Hence, a BUG_ON().
>                          */
>                         BUG_ON(ret);
> -                       pr_warn("%s: CPU%d: Unlisted initial frequency changed to: %u KHz\n",
> -                               __func__, policy->cpu, policy->cur);
> +                       pr_info("%s: CPU%d: Running at unlisted initial frequency: %u KHz, changing to: %u KHz\n",
> +                               __func__, policy->cpu, old_freq, policy->cur);
>                 }
>         }
>
> --

Applied as 5.10-rc material, thanks!