drm/i915: add pipe_config->has_pch_encoder

This is used way too often in the enable/disable paths. And will
be even more useful in the future.

Note that correct semantics of this change highly depend upon
correct updating of intel_crtc->config: Like with all other
modeset state, we need to call ->disable with the old config,
but ->mode_set and ->enable with the new config.

v2: Do not yet use the flag in the ->disable callbacks - atm we don't
yet have support for the information stored in the pipe_config in the
hw state readout code, so this will be wrong at boot-up/resume.

v3: Rebased on top of the hdmi/dp ddi encoder merging.

v4: Fixup stupid rebase error which lead to a NULL vfunc deref.

v5: On haswell the VGA port is on the PCH!

v6: s/IS_HASWELL/HAS_DDI/, spotted by Paulo Zanoni. Also add a missing
parameter name in a function declaration.

v7: Don't forget to git add ...

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 756ae55..1ae2d7f 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -206,10 +206,14 @@
 	return MODE_OK;
 }
 
-static bool intel_crt_mode_fixup(struct drm_encoder *encoder,
-				 const struct drm_display_mode *mode,
-				 struct drm_display_mode *adjusted_mode)
+static bool intel_crt_compute_config(struct intel_encoder *encoder,
+				     struct intel_crtc_config *pipe_config)
 {
+	struct drm_device *dev = encoder->base.dev;
+
+	if (HAS_PCH_SPLIT(dev))
+		pipe_config->has_pch_encoder = true;
+
 	return true;
 }
 
@@ -683,7 +687,6 @@
  */
 
 static const struct drm_encoder_helper_funcs crt_encoder_funcs = {
-	.mode_fixup = intel_crt_mode_fixup,
 	.mode_set = intel_crt_mode_set,
 };
 
@@ -774,6 +777,7 @@
 	else
 		crt->adpa_reg = ADPA;
 
+	crt->base.compute_config = intel_crt_compute_config;
 	crt->base.disable = intel_disable_crt;
 	crt->base.enable = intel_enable_crt;
 	if (I915_HAS_HOTPLUG(dev))