linux-kernel - Re: [PATCH v4 2/5] drm: panel: simple: Defer unprepare delay till next prepare to shorten it

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Date:   Sun, 29 Nov 2020 23:11:32 +0100
From:   Sam Ravnborg <sam@...nborg.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Thierry Reding <thierry.reding@...il.com>, robdclark@...omium.org,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v4 2/5] drm: panel: simple: Defer unprepare delay till
 next prepare to shorten it

Hi Douglas,
On Mon, Nov 09, 2020 at 05:00:56PM -0800, Douglas Anderson wrote:
> It is believed that all of the current users of the "unprepare" delay
> don't actually need to wait the amount of time specified directly in
> the unprepare phase.  The purpose of the delay that's specified is to
> allow the panel to fully power off so that we don't try to power it
> back on before it's managed to full power down.
> 
> Let's use this observation to avoid the fixed delay that we currently
> have.  Instead of delaying, we'll note the current time when the
> unprepare happens.  If someone then tries to prepare the panel later
> and not enough time has passed, we'll do the delay before starting the
> prepare phase.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Applied to drm-misc-next.

	Sam