linux-kernel - Re: [PATCH v2] drm/lima: add governor data with pre-defined thresholds

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Message-ID: <CAKGbVbtaDHmukvfF=sfSmWHVdAYoF6-i4RTzsPQ6zfsjHcGNCw@mail.gmail.com>
Date:   Sat, 30 Jan 2021 21:57:50 +0800
From:   Qiang Yu <yuq825@...il.com>
To:     Christian Hewitt <christianshewitt@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        lima@...ts.freedesktop.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lukasz Luba <lukasz.luba@....com>,
        Steven Price <steven.price@....com>
Subject: Re: [PATCH v2] drm/lima: add governor data with pre-defined thresholds

This patch gets minor improvement on glmark2 (160->162).

Seems there's no way for user to change this value, do we?
Or there's work pending to expose it to sysfs?

Regards,
Qiang

On Thu, Jan 28, 2021 at 3:40 AM Christian Hewitt
<christianshewitt@...il.com> wrote:
>
> This patch adapts the panfrost pre-defined thresholds change [0] to the
> lima driver to improve real-world performance. The upthreshold value has
> been set to ramp GPU frequency to max freq faster (compared to panfrost)
> to compensate for the lower overall performance of utgard devices.
>
> [0] https://patchwork.kernel.org/project/dri-devel/patch/20210121170445.19761-1-lukasz.luba@arm.com/
>
> Signed-off-by: Christian Hewitt <christianshewitt@...il.com>
> ---
> Change since v1: increased upthreshold from 20 to 30, with a soft
> dependency on Lukasz delayed timer patch [0]
>
> [0] https://lore.kernel.org/lkml/20210127105121.20345-1-lukasz.luba@arm.com/
>
>  drivers/gpu/drm/lima/lima_devfreq.c | 10 +++++++++-
>  drivers/gpu/drm/lima/lima_devfreq.h |  2 ++
>  2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c
> index 5686ad4aaf7c..c9854315a0b5 100644
> --- a/drivers/gpu/drm/lima/lima_devfreq.c
> +++ b/drivers/gpu/drm/lima/lima_devfreq.c
> @@ -163,8 +163,16 @@ int lima_devfreq_init(struct lima_device *ldev)
>         lima_devfreq_profile.initial_freq = cur_freq;
>         dev_pm_opp_put(opp);
>
> +       /*
> +        * Setup default thresholds for the simple_ondemand governor.
> +        * The values are chosen based on experiments.
> +        */
> +       ldevfreq->gov_data.upthreshold = 30;
> +       ldevfreq->gov_data.downdifferential = 5;
> +
>         devfreq = devm_devfreq_add_device(dev, &lima_devfreq_profile,
> -                                         DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
> +                                         DEVFREQ_GOV_SIMPLE_ONDEMAND,
> +                                         &ldevfreq->gov_data);
>         if (IS_ERR(devfreq)) {
>                 dev_err(dev, "Couldn't initialize GPU devfreq\n");
>                 ret = PTR_ERR(devfreq);
> diff --git a/drivers/gpu/drm/lima/lima_devfreq.h b/drivers/gpu/drm/lima/lima_devfreq.h
> index 2d9b3008ce77..b0c7c736e81a 100644
> --- a/drivers/gpu/drm/lima/lima_devfreq.h
> +++ b/drivers/gpu/drm/lima/lima_devfreq.h
> @@ -4,6 +4,7 @@
>  #ifndef __LIMA_DEVFREQ_H__
>  #define __LIMA_DEVFREQ_H__
>
> +#include <linux/devfreq.h>
>  #include <linux/spinlock.h>
>  #include <linux/ktime.h>
>
> @@ -18,6 +19,7 @@ struct lima_devfreq {
>         struct opp_table *clkname_opp_table;
>         struct opp_table *regulators_opp_table;
>         struct thermal_cooling_device *cooling;
> +       struct devfreq_simple_ondemand_data gov_data;
>
>         ktime_t busy_time;
>         ktime_t idle_time;
> --
> 2.17.1
>