drm/i915: get a runtime PM reference when the panel VDD is on

And put it when it's off. Otherwise, when you run pm_pc8 from
intel-gpu-tools, and the delayed function that disables VDD runs,
we'll get some messages saying we're touching registers while the HW
is suspended.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -1094,6 +1094,8 @@ void ironlake_edp_panel_vdd_on(struct intel_dp *intel_dp)
 	if (ironlake_edp_have_panel_vdd(intel_dp))
 		return;
 
+	intel_runtime_pm_get(dev_priv);
+
 	DRM_DEBUG_KMS("Turning eDP VDD on\n");
 
 	if (!ironlake_edp_have_panel_power(intel_dp))
@@ -1143,6 +1145,8 @@ static void ironlake_panel_vdd_off_sync(struct intel_dp *intel_dp)
 		DRM_DEBUG_KMS("PP_STATUS: 0x%08x PP_CONTROL: 0x%08x\n",
 		I915_READ(pp_stat_reg), I915_READ(pp_ctrl_reg));
 		msleep(intel_dp->panel_power_down_delay);
+
+		intel_runtime_pm_put(dev_priv);
 	}
 }
 
@@ -1250,6 +1254,9 @@ void ironlake_edp_panel_off(struct intel_dp *intel_dp)
 	intel_dp->want_panel_vdd = false;
 
 	ironlake_wait_panel_off(intel_dp);
+
+	/* We got a reference when we enabled the VDD. */
+	intel_runtime_pm_put(dev_priv);
 }
 
 void ironlake_edp_backlight_on(struct intel_dp *intel_dp)