[PATCH 2/2] drm/i915/mst: Use MST sideband message transaction for dpms

[Dhinakaran Pandiyan]

Use the POWER_DOWN_PHY and POWER_UP_PHY sideband message trasactions to
set power states for downstream sinks. Apart from giving us the ability
to set power state for individual sinks, this fixes the below test for
me

$ xrandr --display :0 --output DP-2-2-8 --off
$ xrandr --display :0 --output DP-2-2-1 --off
$ xrandr --display :0 --output DP-2-2-8 --auto #Black screen
$ xrandr --display :0 --output DP-2-2-1 --auto

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Lyude <lyude at redhat.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/i915/intel_ddi.c    | 6 ++++--
 drivers/gpu/drm/i915/intel_dp_mst.c | 8 ++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 1da3bb2cc4b4..8aebacc0aa31 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2161,7 +2161,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 		intel_prepare_dp_ddi_buffers(encoder);
 
 	intel_ddi_init_dp_buf_reg(encoder);
-	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+	if (!link_mst)
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
 	intel_dp_start_link_train(intel_dp);
 	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
 		intel_dp_stop_link_train(intel_dp);
@@ -2240,7 +2241,8 @@ static void intel_ddi_post_disable(struct intel_encoder *intel_encoder,
 	if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
-		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+		if (old_crtc_state && old_conn_state)
+			intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
 	}
 
 	val = I915_READ(DDI_BUF_CTL(port));
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 8e3aad0ea60b..81e63724e24b 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -167,12 +167,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 	intel_dp->active_mst_links--;
 
 	intel_mst->connector = NULL;
-	if (intel_dp->active_mst_links == 0) {
+	if (intel_dp->active_mst_links == 0)
 		intel_dig_port->base.post_disable(&intel_dig_port->base,
 						  NULL, NULL);
-
-		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
-	}
+	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port,
+				     false);
 }
 
 static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
@@ -197,6 +196,7 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
 
 	DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
 
+	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
 	if (intel_dp->active_mst_links == 0)
 		intel_dig_port->base.pre_enable(&intel_dig_port->base,
 						pipe_config, NULL);
-- 
2.11.0