The digital ports from Ironlake and up have the ability to distinguish between long and short HPD pulses. Displayport 1.1 only uses the short form to request link retraining usually, so we haven't really needed support for it until now. However with DP 1.2 MST we need to handle the short irqs on their own outside the modesetting locking the long hpd's involve. This patch adds the framework to distinguish between short/long to the current code base, to lay the basis for future DP 1.2 MST work. This should mean we get better bisectability in case of regression due to the new irq handling. Signed-off-by: Dave Airlie <airlied@redhat.com>