linux-kernel - Re: [PATCH 1/5] drm/panel-edp: Use ktime_get

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Date:   Thu, 17 Nov 2022 13:14:33 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Drew Davenport <ddavenport@...omium.org>
Cc:     dri-devel@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] drm/panel-edp: Use ktime_get_boottime for delays

Hi,

On Thu, Nov 17, 2022 at 12:39 PM Drew Davenport <ddavenport@...omium.org> wrote:
>
> ktime_get is based on CLOCK_MONOTONIC which stops on suspend. On
> suspend, the time that the panel was powerd off is recorded with
> ktime_get, and on resume this time is compared to the current ktime_get
> time to determine if the driver should wait for the panel to power down
> completely before re-enabling it.
>
> Because we're using ktime_get, this delay doesn't account for the time
> that the device is suspended, during which the power down delay may have
> already elapsed.
>
> Change to use ktime_get_boottime throughout, which uses CLOCK_BOOTTIME
> which does not stop when suspended. This ensures that the resume path
> will not be delayed if the power off delay has already been met while
> the device is suspended.
>
> Signed-off-by: Drew Davenport <ddavenport@...omium.org>
>
> ---
>
>  drivers/gpu/drm/panel/panel-edp.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Douglas Anderson <dianders@...omium.org>