[PATCH 7/9] drm/i915/dp: Implement .set_idle_link_train() for everyone

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

All platforms are capable of explicitly transmitting the idle
pattern. Implement it for everyone (so far it as implemented
only for HSW+).

The immediate benefit is that we gain support for the
POST_LT_ADJ_REQ sequence for all platforms.

Another potential future use would be a pseudo port sync mode on
pre-BDW where we attempt to sync up multiple ports/pipes by trying
to turn on the transcoders at the same time, and switching the
links to normal pixel transmission at the same time.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/g4x_dp.c | 33 +++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
index 372c3683c193..390f9b476a11 100644
--- a/drivers/gpu/drm/i915/display/g4x_dp.c
+++ b/drivers/gpu/drm/i915/display/g4x_dp.c
@@ -621,6 +621,19 @@ cpt_set_link_train(struct intel_dp *intel_dp,
 	intel_de_posting_read(display, intel_dp->output_reg);
 }
 
+static void
+cpt_set_idle_link_train(struct intel_dp *intel_dp,
+			const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(intel_dp);
+
+	intel_dp->DP &= ~DP_LINK_TRAIN_MASK_CPT;
+	intel_dp->DP |= DP_LINK_TRAIN_PAT_IDLE_CPT;
+
+	intel_de_write(display, intel_dp->output_reg, intel_dp->DP);
+	intel_de_posting_read(display, intel_dp->output_reg);
+}
+
 static void
 g4x_set_link_train(struct intel_dp *intel_dp,
 		   const struct intel_crtc_state *crtc_state,
@@ -649,6 +662,19 @@ g4x_set_link_train(struct intel_dp *intel_dp,
 	intel_de_posting_read(display, intel_dp->output_reg);
 }
 
+static void
+g4x_set_idle_link_train(struct intel_dp *intel_dp,
+			const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(intel_dp);
+
+	intel_dp->DP &= ~DP_LINK_TRAIN_MASK;
+	intel_dp->DP |= DP_LINK_TRAIN_PAT_IDLE;
+
+	intel_de_write(display, intel_dp->output_reg, intel_dp->DP);
+	intel_de_posting_read(display, intel_dp->output_reg);
+}
+
 static void intel_dp_enable_port(struct intel_dp *intel_dp,
 				 const struct intel_crtc_state *crtc_state)
 {
@@ -1353,10 +1379,13 @@ bool g4x_dp_init(struct intel_display *display,
 	intel_encoder->audio_disable = g4x_dp_audio_disable;
 
 	if ((display->platform.ivybridge && port == PORT_A) ||
-	    (HAS_PCH_CPT(dev_priv) && port != PORT_A))
+	    (HAS_PCH_CPT(dev_priv) && port != PORT_A)) {
 		dig_port->dp.set_link_train = cpt_set_link_train;
-	else
+		dig_port->dp.set_idle_link_train = cpt_set_idle_link_train;
+	} else {
 		dig_port->dp.set_link_train = g4x_set_link_train;
+		dig_port->dp.set_idle_link_train = g4x_set_idle_link_train;
+	}
 
 	if (display->platform.cherryview)
 		intel_encoder->set_signal_levels = chv_set_signal_levels;
-- 
2.45.3