Re: [PATCH] drm/i915: Ignore long hpds on eDP ports

[Josh Boyer]

On Thu, Nov 27, 2014 at 3:52 PM, Dave Airlie <airlied(a)redhat.com&gt; wrote:
>  From: Ville Syrjälä <ville.syrjala(a)linux.intel.com&gt;
>
>  Turning vdd on/off can generate a long hpd pulse on eDP ports. In order
>  to handle hpd we would need to turn on vdd to perform aux transfers.
>  This would lead to an endless cycle of
>  "vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..."
>
>  So ignore long hpd pulses on eDP ports. eDP panels should be physically
>  tied to the machine anyway so they should not actually disappear and
>  thus don't need long hpd handling. Short hpds are still needed for link
>  re-train and whatnot so we can't just turn off the hpd interrupt
>  entirely for eDP ports. Perhaps we could turn it off whenever the panel
>  is disabled, but just ignoring the long hpd seems sufficient.
>
>  Signed-off-by: Ville Syrjälä <ville.syrjala(a)linux.intel.com&gt;
>  Cc: stable(a)vger.kernel.org
>  Reviewed-by: Dave Airlie <airlied(a)redhat.com&gt;
>  Reviewed-by: Todd Previte <tprevite(a)gmail.com&gt;
>  Signed-off-by: Jani Nikula <jani.nikula(a)intel.com&gt; 
Thanks.  I'll get this applied today.

josh