[PATCH v2 05/11] drm/i915/ddi: Simplify the port enabling via DDI_BUF_CTL

[Imre Deak <imre.deak@intel.com>]

In the past intel_digital_port::dp.prepare_link_retrain() could be
called directly (vs. from a modeset) to retrain an enabled link. In that
case the port had to be first disabled and then re-enabled. That changed
with commit 2885d283cce5 ("drm/i915/dp: Retrain SST links via a modeset
commit"), after which the only way prepare_link_retrain() can be called
is from a modeset during link training when the port is still disabled.
Simplify things accordingly, assuming the disabled port state.

v2: Don't use drm_i915_private in intel_ddi_prepare_link_retrain(). (Jani)

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 1e7ae93340ff4..68c93071720ec 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3765,8 +3765,8 @@ static void mtl_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 	 * necessary disable and enable port
 	 */
 	dp_tp_ctl = intel_de_read(display, dp_tp_ctl_reg(encoder, crtc_state));
-	if (dp_tp_ctl & DP_TP_CTL_ENABLE)
-		mtl_disable_ddi_buf(encoder, crtc_state);
+
+	drm_WARN_ON(display->drm, dp_tp_ctl & DP_TP_CTL_ENABLE);
 
 	/* 6.d Configure and enable DP_TP_CTL with link training pattern 1 selected */
 	dp_tp_ctl = DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_PAT1;
@@ -3805,30 +3805,16 @@ static void mtl_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 					   const struct intel_crtc_state *crtc_state)
 {
+	struct intel_display *display = to_intel_display(intel_dp);
 	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
 	struct intel_encoder *encoder = &dig_port->base;
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	enum port port = encoder->port;
-	u32 dp_tp_ctl, ddi_buf_ctl;
-	bool wait = false;
+	u32 dp_tp_ctl;
 
 	dp_tp_ctl = intel_de_read(dev_priv, dp_tp_ctl_reg(encoder, crtc_state));
 
-	if (dp_tp_ctl & DP_TP_CTL_ENABLE) {
-		ddi_buf_ctl = intel_de_read(dev_priv, DDI_BUF_CTL(port));
-		if (ddi_buf_ctl & DDI_BUF_CTL_ENABLE) {
-			intel_de_write(dev_priv, DDI_BUF_CTL(port),
-				       ddi_buf_ctl & ~DDI_BUF_CTL_ENABLE);
-			wait = true;
-		}
-
-		dp_tp_ctl &= ~DP_TP_CTL_ENABLE;
-		intel_de_write(dev_priv, dp_tp_ctl_reg(encoder, crtc_state), dp_tp_ctl);
-		intel_de_posting_read(dev_priv, dp_tp_ctl_reg(encoder, crtc_state));
-
-		if (wait)
-			intel_wait_ddi_buf_idle(dev_priv, port);
-	}
+	drm_WARN_ON(display->drm, dp_tp_ctl & DP_TP_CTL_ENABLE);
 
 	dp_tp_ctl = DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_PAT1;
 	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST) ||
-- 
2.44.2