drm/i915: finish off reverting eDP VDD changes

This is a small follow-up fix to the series of eDP VDD back and forth
we've had recently. This is effectively a combined revert of three
commits:

commit 2c2894f698fffd8ff53e1e1d3834f9e1035b1f39
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Fri Mar 7 20:05:20 2014 -0300

    drm/i915: properly disable the VDD when disabling the panel

commit b3064154dfd37deb386b1e459c54e1ca2460b3d5
Author: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Date:   Tue Mar 4 00:42:44 2014 +0100

    drm/i915: Don't just say it, actually force edp vdd

commit dff392dbd258381a6c3164f38420593f2d291e3b
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Fri Dec 6 17:32:41 2013 -0200

    drm/i915: don't touch the VDD when disabling the panel

which shows that we're pretty close back to where we started
already. The first two were basically reverting the last, but missing
the WARN. Add that back. We also OCD the intel_ prefix back to
intel_edp_panel_vdd_on() which was lost somewhere in between. The circle
closes.

For future reference, "drm/i915: don't touch the VDD when disabling the
panel" failed to take into account

commit 6cb49835da0426f69a2931bc2a0a8156344b0e41
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun May 20 17:14:50 2012 +0200

    drm/i915: enable vdd when switching off the eDP panel

and

commit 35a38556d900b9cb5dfa2529c93944b847f8a8a4
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Aug 12 22:17:14 2012 +0200

    drm/i915: reorder edp disabling to fix ivb MacBook Air

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -1340,7 +1340,7 @@ static void intel_ddi_post_disable(struct intel_encoder *intel_encoder)
 	if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
-		edp_panel_vdd_on(intel_dp);
+		intel_edp_panel_vdd_on(intel_dp);
 		intel_edp_panel_off(intel_dp);
 	}
 

drivers/gpu/drm/i915/intel_dp.c

@@ -676,7 +676,7 @@ intel_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
 	int reply_bytes;
 	int ret;
 
-	edp_panel_vdd_on(intel_dp);
+	intel_edp_panel_vdd_on(intel_dp);
 	intel_dp_check_edp(intel_dp);
 	/* Set up the command byte */
 	if (mode & MODE_I2C_READ)
@@ -1161,7 +1161,7 @@ static  u32 ironlake_get_pp_control(struct intel_dp *intel_dp)
 	return control;
 }
 
-void edp_panel_vdd_on(struct intel_dp *intel_dp)
+void intel_edp_panel_vdd_on(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1329,6 +1329,8 @@ void intel_edp_panel_off(struct intel_dp *intel_dp)
 
 	edp_wait_backlight_off(intel_dp);
 
+	WARN(!intel_dp->want_panel_vdd, "Need VDD to turn off panel\n");
+
 	pp = ironlake_get_pp_control(intel_dp);
 	/* We need to switch off panel power _and_ force vdd, for otherwise some
 	 * panels get very unhappy and cease to work. */
@@ -1880,7 +1882,7 @@ static void intel_disable_dp(struct intel_encoder *encoder)
 
 	/* Make sure the panel is off before trying to change the mode. But also
 	 * ensure that we have vdd while we switch off the panel. */
-	edp_panel_vdd_on(intel_dp);
+	intel_edp_panel_vdd_on(intel_dp);
 	intel_edp_backlight_off(intel_dp);
 	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 	intel_edp_panel_off(intel_dp);
@@ -1913,7 +1915,7 @@ static void intel_enable_dp(struct intel_encoder *encoder)
 	if (WARN_ON(dp_reg & DP_PORT_EN))
 		return;
 
-	edp_panel_vdd_on(intel_dp);
+	intel_edp_panel_vdd_on(intel_dp);
 	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
 	intel_dp_start_link_train(intel_dp);
 	intel_edp_panel_on(intel_dp);
@@ -2951,7 +2953,7 @@ intel_dp_probe_oui(struct intel_dp *intel_dp)
 	if (!(intel_dp->dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
 		return;
 
-	edp_panel_vdd_on(intel_dp);
+	intel_edp_panel_vdd_on(intel_dp);
 
 	if (intel_dp_aux_native_read_retry(intel_dp, DP_SINK_OUI, buf, 3))
 		DRM_DEBUG_KMS("Sink OUI: %02hx%02hx%02hx\n",
@@ -3748,7 +3750,7 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 		return true;
 
 	/* Cache DPCD and EDID for edp. */
-	edp_panel_vdd_on(intel_dp);
+	intel_edp_panel_vdd_on(intel_dp);
 	has_dpcd = intel_dp_get_dpcd(intel_dp);
 	edp_panel_vdd_off(intel_dp, false);
 

drivers/gpu/drm/i915/intel_drv.h

@@ -762,12 +762,12 @@ bool intel_dp_compute_config(struct intel_encoder *encoder,
 bool intel_dp_is_edp(struct drm_device *dev, enum port port);
 void intel_edp_backlight_on(struct intel_dp *intel_dp);
 void intel_edp_backlight_off(struct intel_dp *intel_dp);
+void intel_edp_panel_vdd_on(struct intel_dp *intel_dp);
 void intel_edp_panel_on(struct intel_dp *intel_dp);
 void intel_edp_panel_off(struct intel_dp *intel_dp);
 void intel_edp_psr_enable(struct intel_dp *intel_dp);
 void intel_edp_psr_disable(struct intel_dp *intel_dp);
 void intel_edp_psr_update(struct drm_device *dev);
-void edp_panel_vdd_on(struct intel_dp *intel_dp);
 
 
 /* intel_dsi.c */