drm/i915: group link_standby setup and let this info visible everywhere.

No functional changes on this patch. Just grouping the link_standy decision
to avoid miss any change. Also making this info available everywhere
which will help to decide when to use vbt's tp time on following patch.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Durgadoss R <durgadoss.r@intel.com>
[danvet: Slight editing of the commit message which was one huge
run-on sentence.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -789,6 +789,7 @@ struct i915_psr {
 	bool active;
 	struct delayed_work work;
 	unsigned busy_frontbuffer_bits;
+	bool link_standby;
 };
 
 enum intel_pch {

drivers/gpu/drm/i915/intel_psr.c

@@ -143,7 +143,6 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t aux_clock_divider;
 	int precharge = 0x3;
-	bool only_standby = dev_priv->vbt.psr.full_link;
 	static const uint8_t aux_msg[] = {
 		[0] = DP_AUX_NATIVE_WRITE << 4,
 		[1] = DP_SET_POWER >> 8,
@@ -157,11 +156,8 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
 
 	aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, 0);
 
-	if (IS_BROADWELL(dev) && dig_port->port != PORT_A)
-		only_standby = true;
-
 	/* Enable PSR in sink */
-	if (intel_dp->psr_dpcd[1] & DP_PSR_NO_TRAIN_ON_EXIT || only_standby)
+	if (dev_priv->psr.link_standby)
 		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
 				   DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE);
 	else
@@ -226,12 +222,8 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
 			       dev_priv->vbt.psr.idle_frames + 1 : 2;
 	uint32_t val = 0x0;
 	const uint32_t link_entry_time = EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
-	bool only_standby = dev_priv->vbt.psr.full_link;
-
-	if (IS_BROADWELL(dev) && dig_port->port != PORT_A)
-		only_standby = true;
 
-	if (intel_dp->psr_dpcd[1] & DP_PSR_NO_TRAIN_ON_EXIT || only_standby) {
+	if (dev_priv->psr.link_standby) {
 		val |= EDP_PSR_LINK_STANDBY;
 		val |= EDP_PSR_TP2_TP3_TIME_0us;
 		val |= EDP_PSR_TP1_TIME_0us;
@@ -341,6 +333,13 @@ void intel_psr_enable(struct intel_dp *intel_dp)
 	if (!intel_psr_match_conditions(intel_dp))
 		goto unlock;
 
+	/* First we check VBT, but we must respect sink and source
+	 * known restrictions */
+	dev_priv->psr.link_standby = dev_priv->vbt.psr.full_link;
+	if ((intel_dp->psr_dpcd[1] & DP_PSR_NO_TRAIN_ON_EXIT) ||
+	    (IS_BROADWELL(dev) && intel_dig_port->port != PORT_A))
+		dev_priv->psr.link_standby = true;
+
 	dev_priv->psr.busy_frontbuffer_bits = 0;
 
 	if (HAS_DDI(dev)) {