drm/i915/psr: Nuke aux frame sync

eDP spec states that aux frame is required to do PSR2 selective
update but i915 don't fully implement it. It sends the aux frame
sync messages but the value is always zero as the GTC is not enabled
in driver.

Through tests was findout that pannels can do selective update when
the y-coordinate is also included in SDP, that is why it is required
to run PSR2 in i915.

A dummy value is not useful at all to sink, so removing everything
related to aux frame sync, if GTC is enabled we can bring this back.

Cc: Vathsala Nagaraju <vathsala.nagaraju@intel.com>
Acked-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: NJosé Roberto de Souza <jose.souza@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180328223046.16125-3-jose.souza@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -603,7 +603,6 @@ struct i915_psr {
 	struct delayed_work work;
 	unsigned busy_frontbuffer_bits;
 	bool psr2_support;
-	bool aux_frame_sync;
 	bool link_standby;
 	bool y_cord_support;
 	bool colorimetry_support;

drivers/gpu/drm/i915/intel_psr.c

@@ -137,16 +137,9 @@ void intel_psr_init_dpcd(struct intel_dp *intel_dp)
 
 	if (INTEL_GEN(dev_priv) >= 9 &&
 	    (intel_dp->psr_dpcd[0] & DP_PSR2_IS_SUPPORTED)) {
-		uint8_t frame_sync_cap;
 
 		dev_priv->psr.sink_support = true;
-		if (drm_dp_dpcd_readb(&intel_dp->aux,
-				      DP_SINK_DEVICE_AUX_FRAME_SYNC_CAP,
-				      &frame_sync_cap) != 1)
-			frame_sync_cap = 0;
-		dev_priv->psr.aux_frame_sync = frame_sync_cap & DP_AUX_FRAME_SYNC_CAP;
-		/* PSR2 needs frame sync as well */
-		dev_priv->psr.psr2_support = dev_priv->psr.aux_frame_sync;
+		dev_priv->psr.psr2_support = true;
 		DRM_DEBUG_KMS("PSR2 %s on sink",
 			      dev_priv->psr.psr2_support ? "supported" : "not supported");
 
@@ -268,12 +261,6 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
 	struct drm_device *dev = dig_port->base.base.dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
-
-	/* Enable AUX frame sync at sink */
-	if (dev_priv->psr.aux_frame_sync)
-		drm_dp_dpcd_writeb(&intel_dp->aux,
-				DP_SINK_DEVICE_AUX_FRAME_SYNC_CONF,
-				DP_AUX_FRAME_SYNC_ENABLE);
 	/* Enable ALPM at sink for psr2 */
 	if (dev_priv->psr.psr2_support && dev_priv->psr.alpm)
 		drm_dp_dpcd_writeb(&intel_dp->aux,
@@ -712,11 +699,6 @@ static void hsw_psr_disable(struct intel_dp *intel_dp,
 		i915_reg_t psr_status;
 		u32 psr_status_mask;
 
-		if (dev_priv->psr.aux_frame_sync)
-			drm_dp_dpcd_writeb(&intel_dp->aux,
-					DP_SINK_DEVICE_AUX_FRAME_SYNC_CONF,
-					0);
-
 		if (dev_priv->psr.psr2_support) {
 			psr_status = EDP_PSR2_STATUS;
 			psr_status_mask = EDP_PSR2_STATUS_STATE_MASK;
@@ -860,10 +842,6 @@ static void intel_psr_exit(struct drm_i915_private *dev_priv)
 		return;
 
 	if (HAS_DDI(dev_priv)) {
-		if (dev_priv->psr.aux_frame_sync)
-			drm_dp_dpcd_writeb(&intel_dp->aux,
-					DP_SINK_DEVICE_AUX_FRAME_SYNC_CONF,
-					0);
 		if (dev_priv->psr.psr2_support) {
 			val = I915_READ(EDP_PSR2_CTL);
 			WARN_ON(!(val & EDP_PSR2_ENABLE));