drm/i915: Don't touch South Display when PCH_NOP

Interrupts, clock gating, LVDS, and GMBUS are all within the, "this will
be bad for CPU" range when we have PCH_NOP.

There is a bit of a hack in init clock gating. We want to do most of the
clock gating, but the part we skip will hang the system. It could
probably be abstracted a bit better, but I don't feel it's too
unsightly.

v2: Use inverse HAS_PCH_NOP check (Jani)

v3: Actually do what I claimed in v2 (spotted by Daniel)
Merge Ivybridge IRQ handler PCH check to decrease whitespace (Daniel)
Move LVDS bail into this patch (Ben)

v4: logical rebase conflict resolution with SDEIIR (Ben)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

Brush up patch a bit and resolve conflicts:
- Adjust PCH_NOP checks due to Egbert's hpd handling rework.
- Addd a PCH_NOP check in the irq uninstall code.
- Resolve conflicts with Paulo's SDE irq handling race fix.

v5: Drop the added hunks in the ilk irq handler again, they're bogus.
OOps.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 13a0666..17f157a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3890,7 +3890,8 @@
 	snpcr |= GEN6_MBC_SNPCR_MED;
 	I915_WRITE(GEN6_MBCUNIT_SNPCR, snpcr);
 
-	cpt_init_clock_gating(dev);
+	if (!HAS_PCH_NOP(dev))
+		cpt_init_clock_gating(dev);
 
 	gen6_check_mch_setup(dev);
 }