linux-kernel - Re: [PATCH] powercap: DTPM: Fix unneeded conversion to micro-Watts

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Message-ID: <CAJZ5v0hun3D29w0DMgaSoaGpLNLP4dWN-mYpRHYESdFwP6iRsQ@mail.gmail.com>
Date:   Tue, 28 Nov 2023 15:17:21 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        daniel.lezcano@...aro.org, rafael@...nel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] powercap: DTPM: Fix unneeded conversion to micro-Watts

On Mon, Nov 27, 2023 at 10:27 AM Lukasz Luba <lukasz.luba@....com> wrote:
>
> The Power values coming from the Energy Model are already in uW.
> The PowerCap and DTPM framework operate on uW, thus all places should
> just use the values from EM. Fix the code which left and still does
> the unneeded conversion.
>
> Fixes: ae6ccaa65038 (PM: EM: convert power field to micro-Watts precision and align drivers)
> Cc: <stable@...r.kernel.org> # v5.19+
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
> Hi Daniel,
>
> I have found an issue due to the uW in the EM. My apologies for that.

No need to apologize, you are making the code better.

> I have check those with the Rockpi dev board with your DTPM module there.
> BTW, if you like to check the DTPM_devfreq there, you can apply that
> patch. It should create EM for your GPU there and setup DTPM GPU:
> https://lore.kernel.org/all/20231127081511.1911706-1-lukasz.luba@arm.com/
>
> Regards,
> Lukasz
>
>
>  drivers/powercap/dtpm_cpu.c     |  6 +-----
>  drivers/powercap/dtpm_devfreq.c | 11 +++--------
>  2 files changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> index 2ff7717530bf..8a2f18fa3faf 100644
> --- a/drivers/powercap/dtpm_cpu.c
> +++ b/drivers/powercap/dtpm_cpu.c
> @@ -24,7 +24,6 @@
>  #include <linux/of.h>
>  #include <linux/pm_qos.h>
>  #include <linux/slab.h>
> -#include <linux/units.h>
>
>  struct dtpm_cpu {
>         struct dtpm dtpm;
> @@ -104,8 +103,7 @@ static u64 get_pd_power_uw(struct dtpm *dtpm)
>                 if (pd->table[i].frequency < freq)
>                         continue;
>
> -               return scale_pd_power_uw(pd_mask, pd->table[i].power *
> -                                        MICROWATT_PER_MILLIWATT);
> +               return scale_pd_power_uw(pd_mask, pd->table[i].power);
>         }
>
>         return 0;
> @@ -122,11 +120,9 @@ static int update_pd_power_uw(struct dtpm *dtpm)
>         nr_cpus = cpumask_weight(&cpus);
>
>         dtpm->power_min = em->table[0].power;
> -       dtpm->power_min *= MICROWATT_PER_MILLIWATT;
>         dtpm->power_min *= nr_cpus;
>
>         dtpm->power_max = em->table[em->nr_perf_states - 1].power;
> -       dtpm->power_max *= MICROWATT_PER_MILLIWATT;
>         dtpm->power_max *= nr_cpus;
>
>         return 0;
> diff --git a/drivers/powercap/dtpm_devfreq.c b/drivers/powercap/dtpm_devfreq.c
> index 91276761a31d..612c3b59dd5b 100644
> --- a/drivers/powercap/dtpm_devfreq.c
> +++ b/drivers/powercap/dtpm_devfreq.c
> @@ -39,10 +39,8 @@ static int update_pd_power_uw(struct dtpm *dtpm)
>         struct em_perf_domain *pd = em_pd_get(dev);
>
>         dtpm->power_min = pd->table[0].power;
> -       dtpm->power_min *= MICROWATT_PER_MILLIWATT;
>
>         dtpm->power_max = pd->table[pd->nr_perf_states - 1].power;
> -       dtpm->power_max *= MICROWATT_PER_MILLIWATT;
>
>         return 0;
>  }
> @@ -54,13 +52,10 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
>         struct device *dev = devfreq->dev.parent;
>         struct em_perf_domain *pd = em_pd_get(dev);
>         unsigned long freq;
> -       u64 power;
>         int i;
>
>         for (i = 0; i < pd->nr_perf_states; i++) {
> -
> -               power = pd->table[i].power * MICROWATT_PER_MILLIWATT;
> -               if (power > power_limit)
> +               if (pd->table[i].power > power_limit)
>                         break;
>         }
>
> @@ -68,7 +63,7 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
>
>         dev_pm_qos_update_request(&dtpm_devfreq->qos_req, freq);
>
> -       power_limit = pd->table[i - 1].power * MICROWATT_PER_MILLIWATT;
> +       power_limit = pd->table[i - 1].power;
>
>         return power_limit;
>  }
> @@ -110,7 +105,7 @@ static u64 get_pd_power_uw(struct dtpm *dtpm)
>                 if (pd->table[i].frequency < freq)
>                         continue;
>
> -               power = pd->table[i].power * MICROWATT_PER_MILLIWATT;
> +               power = pd->table[i].power;
>                 power *= status.busy_time;
>                 power >>= 10;
>
> --

Applied as 6.7-rc material, thanks!