linux-kernel - Re: [Intel-gfx] [PATCH 9/9] drm/i915: Disable eDP VDD in a delayed work proc instead of synchronously

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Date:	Wed, 21 Sep 2011 09:47:59 +0530
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Keith Packard <keithp@...thp.com>
Cc:	Dave Airlie <airlied@...hat.com>, intel-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 9/9] drm/i915: Disable eDP VDD in a delayed
 work proc instead of synchronously

On Mon, 19 Sep 2011 15:22:03 -0700
Keith Packard <keithp@...thp.com> wrote:

> There's no good reason to turn off the eDP force VDD bit synchronously
> while probing devices; that just sticks a huge delay into all mode
> setting paths. Instead, queue a delayed work proc to disable the VDD
> force bit and then remember when that fires to ensure that the
> appropriate delay is respected before trying to turn it back on.
> 
> Signed-off-by: Keith Packard <keithp@...thp.com>
> ---

I'm worried this makes our PPS even more complex and hard to follow.
I'd rather see VDD AUX applied only when we need it (dpms, mode set and
detect; for hotplug we can assume the panel is alive) and that we
carefully disable it after waiting for a time after a full PPS on
sequence when doing a mode set or dpms on command.

Having all the power stuff at the highest levels would be clearest I
think.

Jesse
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