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

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Date:   Fri, 11 Nov 2022 12:44:20 -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] drm/panel-edp: Use ktime_get_boottime for delays

Hi,

On Thu, Nov 10, 2022 at 1:51 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(-)

Nice!

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

My plan will be to land this to drm-misc-next early next week (Tuesday
maybe?) unless someone has any objections.

BTW: any chance you'd be willing to post against two similar drivers:
panel-simple.c and panel-samsung-atna33xc20.c? They have nearly the
same code (and, yes, these drivers are purposely copies since there
was overall consensus that having one giant panel driver to handle all
possible panels was getting far too confusing)

-Doug