linux-kernel - Re: [Intel-gfx] drm/i915: A selection of display port fixes

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Date:	Tue, 26 Jul 2011 14:48:13 -0400
From:	Adam Jackson <ajax@...hat.com>
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] drm/i915: A selection of display port fixes

On Mon, 2011-07-25 at 23:36 -0700, Keith Packard wrote:
> [PATCH 1/5] drm/i915: Use dp_detect_common in hotplug helper
>  [PATCH 2/5] drm/i915: Rename i915_dp_detect_common to
>  [PATCH 3/5] drm/i915: In intel_dp_init, replace read of DPCD with
> 
> These three are simple cleanups to centralize all places where the
> DPCD block was read from the device. Now everyone shares the same
> function, and that function retries the reads.

Reviewed-by: Adam Jackson <ajax@...hat.com>

>  [PATCH 4/5] drm/i915: Delay 250ms before running the hotplug code
> 
> I was experimenting with DP hotplugging -- moving the plug in and out
> of the jack very slowly and discovered that the hotplug interrupt
> occurred well before or after the link for the aux data channel was
> connected or disconnected. The result of this was that a sufficiently
> rapid cycle back through user mode could easily beat the motion of the
> plug and cause the hotplug detection to get the wrong status. Sticking
> a 250ms delay before doing anything gives the user sufficient time to
> actually get the plug connected or disconnected.

At the very least this should instead be queue_delayed_work().  But if
we're going to delay, can we instead set up PCH_PORT_HOTPLUG to do a
100ms delay for us?  I'll try this locally, at any rate.

>  [PATCH 5/5] drm/i915: DP_PIPE_ENABLED must check transcoder on CPT
> 
> <snip>
>
> Turns out the bug wasn't that the mode setting code was doing it wrong
> and turning the DP2 output off intentionally as a part of the mode
> change. Instead, the intel driver was trying to adjust the PCH link
> for the LVDS1 output and thought it needed to turn the DP2 output off
> because it mistakenly believed the DP2 output was sharing the same
> pipe as the LVDS1 output. Just a matter of using the wrong mechanism
> to detect which pipe the DP2 output was connected to.

Reviewed-by: Adam Jackson <ajax@...hat.com>

- ajax

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