linux-kernel - Re: [PATCH] drm/lima: Use delayed timer as default in devfreq profile

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Message-ID: <CAKGbVbsn=xVEa0=c3rywRShVZD18LkmLZ1qDUuDsrT5KnTjr6g@mail.gmail.com>
Date:   Sat, 30 Jan 2021 21:51:05 +0800
From:   Qiang Yu <yuq825@...il.com>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, lima@...ts.freedesktop.org,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        christianshewitt@...il.com
Subject: Re: [PATCH] drm/lima: Use delayed timer as default in devfreq profile

Thanks for the patch. But I can't observe any difference on glmark2
with or without this patch.
Maybe you can provide other test which can benefit from it.

Considering it will wake up CPU more frequently, and user may choose
to change this by sysfs,
I'd like to not apply it.

Regards,
Qiang

On Wed, Jan 27, 2021 at 6:51 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> Devfreq framework supports 2 modes for monitoring devices.
> Use delayed timer as default instead of deferrable timer
> in order to monitor the GPU status regardless of CPU idle.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
> Hi all,
>
> I've missed the Lima driver while working on Panfrost patch for fixing
> the issue with default devfreq framework polling mode. More about this
> and the patch, can be found here [1].
>
> Regards,
> Lukasz Luba
>
> [1] https://lore.kernel.org/lkml/20210105164111.30122-1-lukasz.luba@arm.com/
>
>  drivers/gpu/drm/lima/lima_devfreq.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/lima/lima_devfreq.c b/drivers/gpu/drm/lima/lima_devfreq.c
> index 5686ad4aaf7c..f1c9eb3e71bd 100644
> --- a/drivers/gpu/drm/lima/lima_devfreq.c
> +++ b/drivers/gpu/drm/lima/lima_devfreq.c
> @@ -81,6 +81,7 @@ static int lima_devfreq_get_dev_status(struct device *dev,
>  }
>
>  static struct devfreq_dev_profile lima_devfreq_profile = {
> +       .timer = DEVFREQ_TIMER_DELAYED,
>         .polling_ms = 50, /* ~3 frames */
>         .target = lima_devfreq_target,
>         .get_dev_status = lima_devfreq_get_dev_status,
> --
> 2.17.1
>