drm/i915: IBX+ doesn't have separate vsync/hsync controls on the VGA DAC

When the PCH split occurred, hw dropped support for separate hsync and
vsync disable in the VGA DAC.  So add a PCH specific DPMS function that
just uses the port enable bit for controlling DPMS states.

Before this fix, when anything other than a full DPMS off occurred,
the VGA port would be left enabled and scanning out while all the other
heads would turn off as expected.

v2: duplicate encoder helper vtable into pch and gmch versions (Daniel)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48491
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: s/intel_crt_dpms/gmch_crt_dpms as suggested by Chris.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_crt.c

@@ -55,18 +55,36 @@ static struct intel_crt *intel_attached_crt(struct drm_connector *connector)
 			    struct intel_crt, base);
 }
 
-static void intel_crt_dpms(struct drm_encoder *encoder, int mode)
+static void pch_crt_dpms(struct drm_encoder *encoder, int mode)
 {
 	struct drm_device *dev = encoder->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 temp, reg;
+	u32 temp;
 
-	if (HAS_PCH_SPLIT(dev))
-		reg = PCH_ADPA;
-	else
-		reg = ADPA;
+	temp = I915_READ(PCH_ADPA);
+	temp &= ~ADPA_DAC_ENABLE;
+
+	switch (mode) {
+	case DRM_MODE_DPMS_ON:
+		temp |= ADPA_DAC_ENABLE;
+		break;
+	case DRM_MODE_DPMS_STANDBY:
+	case DRM_MODE_DPMS_SUSPEND:
+	case DRM_MODE_DPMS_OFF:
+		/* Just leave port enable cleared */
+		break;
+	}
+
+	I915_WRITE(PCH_ADPA, temp);
+}
 
-	temp = I915_READ(reg);
+static void gmch_crt_dpms(struct drm_encoder *encoder, int mode)
+{
+	struct drm_device *dev = encoder->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 temp;
+
+	temp = I915_READ(ADPA);
 	temp &= ~(ADPA_HSYNC_CNTL_DISABLE | ADPA_VSYNC_CNTL_DISABLE);
 	temp &= ~ADPA_DAC_ENABLE;
 
@@ -85,7 +103,7 @@ static void intel_crt_dpms(struct drm_encoder *encoder, int mode)
 		break;
 	}
 
-	I915_WRITE(reg, temp);
+	I915_WRITE(ADPA, temp);
 }
 
 static int intel_crt_mode_valid(struct drm_connector *connector,
@@ -516,12 +534,20 @@ static void intel_crt_reset(struct drm_connector *connector)
  * Routines for controlling stuff on the analog port
  */
 
-static const struct drm_encoder_helper_funcs intel_crt_helper_funcs = {
-	.dpms = intel_crt_dpms,
+static const struct drm_encoder_helper_funcs pch_encoder_funcs = {
+	.mode_fixup = intel_crt_mode_fixup,
+	.prepare = intel_encoder_prepare,
+	.commit = intel_encoder_commit,
+	.mode_set = intel_crt_mode_set,
+	.dpms = pch_crt_dpms,
+};
+
+static const struct drm_encoder_helper_funcs gmch_encoder_funcs = {
 	.mode_fixup = intel_crt_mode_fixup,
 	.prepare = intel_encoder_prepare,
 	.commit = intel_encoder_commit,
 	.mode_set = intel_crt_mode_set,
+	.dpms = gmch_crt_dpms,
 };
 
 static const struct drm_connector_funcs intel_crt_connector_funcs = {
@@ -567,6 +593,7 @@ void intel_crt_init(struct drm_device *dev)
 	struct intel_crt *crt;
 	struct intel_connector *intel_connector;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	const struct drm_encoder_helper_funcs *encoder_helper_funcs;
 
 	/* Skip machines without VGA that falsely report hotplug events */
 	if (dmi_check_system(intel_no_crt))
@@ -602,7 +629,12 @@ void intel_crt_init(struct drm_device *dev)
 		connector->interlace_allowed = 1;
 	connector->doublescan_allowed = 0;
 
-	drm_encoder_helper_add(&crt->base.base, &intel_crt_helper_funcs);
+	if (HAS_PCH_SPLIT(dev))
+		encoder_helper_funcs = &pch_encoder_funcs;
+	else
+		encoder_helper_funcs = &gmch_encoder_funcs;
+
+	drm_encoder_helper_add(&crt->base.base, encoder_helper_funcs);
 	drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);
 
 	drm_sysfs_connector_add(connector);