drm/i915: make sure VDD is turned off during system suspend

Atm we may leave eDP VDD enabled during system suspend after the CRTCs
are disabled through an HPD->DPCD read event. So disable VDD during
suspend at a point when no HPDs can occur.

Note that runtime suspend doesn't have the same problem, since there the
RPM ref held by VDD provides already the needed serialization.

v2:
- add note to commit message about the runtime suspend path (Ville)
- use edp_panel_vdd_off_sync(), so we can keep the WARN in
  edp_panel_vdd_off() (Ville)
v3:
- rebased on -fixes (for_each_intel_encoder()->list_for_each_entry())
  (Imre)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v2)
Cc: stable@vger.kernel.org (3.16+)
[Jani: fix sparse warning reported by Fengguang Wu]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 3f9c8f6b2418..e27cdbe9d524 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -509,6 +509,21 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 	cancel_delayed_work_sync(&dev_priv->hotplug_reenable_work);
 }
 
+static void intel_suspend_encoders(struct drm_i915_private *dev_priv)
+{
+	struct drm_device *dev = dev_priv->dev;
+	struct drm_encoder *encoder;
+
+	drm_modeset_lock_all(dev);
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
+
+		if (intel_encoder->suspend)
+			intel_encoder->suspend(intel_encoder);
+	}
+	drm_modeset_unlock_all(dev);
+}
+
 static int i915_drm_freeze(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -555,6 +570,8 @@ static int i915_drm_freeze(struct drm_device *dev)
 		intel_runtime_pm_disable_interrupts(dev);
 		intel_hpd_cancel_work(dev_priv);
 
+		intel_suspend_encoders(dev_priv);
+
 		intel_suspend_gt_powersave(dev);
 
 		intel_modeset_suspend_hw(dev);