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, 11 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a520188e6d97..39b643163846 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4003,6 +4003,16 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
 	kfree(intel_dig_port);
 }
 
+static void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
+
+	if (!is_edp(intel_dp))
+		return;
+
+	edp_panel_vdd_off_sync(intel_dp);
+}
+
 static void intel_dp_encoder_reset(struct drm_encoder *encoder)
 {
 	intel_edp_panel_vdd_sanitize(to_intel_encoder(encoder));
@@ -4731,6 +4741,7 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 	intel_encoder->disable = intel_disable_dp;
 	intel_encoder->get_hw_state = intel_dp_get_hw_state;
 	intel_encoder->get_config = intel_dp_get_config;
+	intel_encoder->suspend = intel_dp_encoder_suspend;
 	if (IS_CHERRYVIEW(dev)) {
 		intel_encoder->pre_pll_enable = chv_dp_pre_pll_enable;
 		intel_encoder->pre_enable = chv_pre_enable_dp;