linux-kernel - Re: [PATCH] thermal/drivers/cpufreq_cooling: Fix wrong frequency converted from power

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Message-ID: <CAHLCerNnJELC=ZhiG7XFbRLk8GgkSSLEPncGt-Yf9yAeDe=9NA@mail.gmail.com>
Date:   Mon, 22 Jun 2020 14:45:57 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     Finley Xiao <finley.xiao@...k-chips.com>
Cc:     xf@...k-chips.com, Heiko Stuebner <heiko@...ech.de>,
        Amit Daniel Kachhap <amit.kachhap@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Javi Merino <javi.merino@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        linux-rockchip@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        huangtao@...k-chips.com, tony.xie@...k-chips.com, cl@...k-chips.com
Subject: Re: [PATCH] thermal/drivers/cpufreq_cooling: Fix wrong frequency
 converted from power

On Fri, Jun 19, 2020 at 7:21 AM Finley Xiao <finley.xiao@...k-chips.com> wrote:
>
> The function cpu_power_to_freq is used to find a frequency and set the
> cooling device to consume at most the power to be converted. For example,
> if the power to be converted is 80mW, and the em table is as follow.
> struct em_cap_state table[] = {
>         /* KHz     mW */
>         { 1008000, 36, 0 },
>         { 1200000, 49, 0 },
>         { 1296000, 59, 0 },
>         { 1416000, 72, 0 },
>         { 1512000, 86, 0 },
> };
> The target frequency should be 1416000KHz, not 1512000KHz.
>
> Fixes: 349d39dc5739 ("thermal: cpu_cooling: merge frequency and power tables")
> Signed-off-by: Finley Xiao <finley.xiao@...k-chips.com>

Reviewed-by: Amit Kucheria <amit.kucheria@...aro.org>

> ---
>  drivers/thermal/cpufreq_cooling.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
> index 9e124020519f..6c0e1b053126 100644
> --- a/drivers/thermal/cpufreq_cooling.c
> +++ b/drivers/thermal/cpufreq_cooling.c
> @@ -123,12 +123,12 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
>  {
>         int i;
>
> -       for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
> -               if (power > cpufreq_cdev->em->table[i].power)
> +       for (i = cpufreq_cdev->max_level; i >= 0; i--) {
> +               if (power >= cpufreq_cdev->em->table[i].power)
>                         break;
>         }
>
> -       return cpufreq_cdev->em->table[i + 1].frequency;
> +       return cpufreq_cdev->em->table[i].frequency;
>  }
>
>  /**
> --
> 2.11.0
>
>
>