drm/i915/psr: Avoid initializing PSR if there is no sink support.

DPCD read for the eDP is complete by the time intel_psr_init() is
called, which means we can avoid initializing PSR structures and state
if there is no sink support.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180103213824.1405-3-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2521,14 +2521,19 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
 	u32 stat[3];
 	enum pipe pipe;
 	bool enabled = false;
+	bool sink_support;
 
 	if (!HAS_PSR(dev_priv))
 		return -ENODEV;
 
+	sink_support = dev_priv->psr.sink_support;
+	seq_printf(m, "Sink_Support: %s\n", yesno(sink_support));
+	if (!sink_support)
+		return 0;
+
 	intel_runtime_pm_get(dev_priv);
 
 	mutex_lock(&dev_priv->psr.lock);
-	seq_printf(m, "Sink_Support: %s\n", yesno(dev_priv->psr.sink_support));
 	seq_printf(m, "Enabled: %s\n", yesno((bool)dev_priv->psr.enabled));
 	seq_printf(m, "Active: %s\n", yesno(dev_priv->psr.active));
 	seq_printf(m, "Busy frontbuffer bits: 0x%03x\n",

drivers/gpu/drm/i915/intel_psr.c

@@ -503,6 +503,9 @@ void intel_psr_enable(struct intel_dp *intel_dp,
 	if (!crtc_state->has_psr)
 		return;
 
+	if (WARN_ON(!CAN_PSR(dev_priv)))
+		return;
+
 	WARN_ON(dev_priv->drrs.dp);
 	mutex_lock(&dev_priv->psr.lock);
 	if (dev_priv->psr.enabled) {
@@ -633,6 +636,9 @@ void intel_psr_disable(struct intel_dp *intel_dp,
 	if (!old_crtc_state->has_psr)
 		return;
 
+	if (WARN_ON(!CAN_PSR(dev_priv)))
+		return;
+
 	mutex_lock(&dev_priv->psr.lock);
 	if (!dev_priv->psr.enabled) {
 		mutex_unlock(&dev_priv->psr.lock);
@@ -913,6 +919,9 @@ void intel_psr_init(struct drm_i915_private *dev_priv)
 	dev_priv->psr_mmio_base = IS_HASWELL(dev_priv) ?
 		HSW_EDP_PSR_BASE : BDW_EDP_PSR_BASE;
 
+	if (!dev_priv->psr.sink_support)
+		return;
+
 	/* Per platform default: all disabled. */
 	if (i915_modparams.enable_psr == -1)
 		i915_modparams.enable_psr = 0;