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>

3 files changed, 34 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);
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;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index fe3431f96900..b8c8bbd8e5f9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -153,6 +153,12 @@ struct intel_encoder {
          * be set correctly before calling this function. */
         void (*get_config)(struct intel_encoder *,
                            struct intel_crtc_config *pipe_config);
+        /*
+         * Called during system suspend after all pending requests for the
+         * encoder are flushed (for example for DP AUX transactions) and
+         * device interrupts are disabled.
+         */
+        void (*suspend)(struct intel_encoder *);
         int crtc_mask;
         enum hpd_pin hpd_pin;
 };