Re: [PATCH v2 1/2] drm/i915/ilk: Don't attempt to register eDP if LVDS was detected

Chris Wilson
2016-06-20T08:43:33Z

On Sat, Jun 18, 2016 at 12:29:24AM +0300, Imre Deak wrote:
> Atm on ILK we attempt to detect if eDP is present even if LVDS was
> already detected and an encoder for it was registered. This involves
> trying to read out the eDP EDID, which in turn needs the same power
> sequencer that LVDS uses. Poking at the VDD line at an unexpected time
> may or may not interfere with the LVDS panel, but it's probably safer to
> prevent this. Registering both an LVDS and an eDP connector would also
> present a similar problem accessing the shared PPS at any point later in
> an unexpected way.
>
> We also need this to be able fix PPS initialization before its first use
> in the next patch. For that we want to be sure that PPS is not in use
> by LVDS.
>
> v2:
> - Split out the PPS init fix to a separate patch. (Chris)
> - Add comment about eDP init depending on LVDS init. (Chris)
> - Make the use of the intel_encoder ptr less error prone.
>
> CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
> CC: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Regardless of the discussion we are having about whether there may be
more complications, or if we have missed something, this patch seems a
sensible guard.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris

--
Chris Wilson, Intel Open Source Technology Centre