drm/i915/ddi: enable ACT handling for 128b/132b SST

Add ACT handling for 128b/132b SST enable/disable.

This is preparation for enabling 128b/132b SST. This path is not
reachable yet.

v2:
- Check for !is_hdmi (Imre)
- Add disable sequence (Imre)

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b0226471f9445d988917cee49dbbd93a1493f3c7.1735912293.git.jani.nikula@intel.com

Author: jnikula

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -3199,7 +3199,9 @@ static void intel_ddi_post_disable_hdmi_or_sst(struct intel_atomic_state *state,
 {
 	struct intel_display *display = to_intel_display(encoder);
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 	struct intel_crtc *pipe_crtc;
+	bool is_hdmi = intel_crtc_has_type(old_crtc_state, INTEL_OUTPUT_HDMI);
 	int i;
 
 	for_each_pipe_crtc_modeset_disable(display, pipe_crtc, old_crtc_state, i) {
@@ -3211,6 +3213,20 @@ static void intel_ddi_post_disable_hdmi_or_sst(struct intel_atomic_state *state,
 
 	intel_disable_transcoder(old_crtc_state);
 
+	/* 128b/132b SST */
+	if (!is_hdmi && intel_dp_is_uhbr(old_crtc_state)) {
+		/* VCPID 1, start slot 0 for 128b/132b, clear */
+		drm_dp_dpcd_write_payload(&intel_dp->aux, 1, 0, 0);
+
+		intel_ddi_clear_act_sent(encoder, old_crtc_state);
+
+		intel_de_rmw(display, TRANS_DDI_FUNC_CTL(display, old_crtc_state->cpu_transcoder),
+			     TRANS_DDI_DP_VC_PAYLOAD_ALLOC, 0);
+
+		intel_ddi_wait_for_act_sent(encoder, old_crtc_state);
+		drm_dp_dpcd_poll_act_handled(&intel_dp->aux, 0);
+	}
+
 	intel_ddi_disable_transcoder_func(old_crtc_state);
 
 	for_each_pipe_crtc_modeset_disable(display, pipe_crtc, old_crtc_state, i) {
@@ -3493,6 +3509,19 @@ static void intel_ddi_enable(struct intel_atomic_state *state,
 	/* Enable/Disable DP2.0 SDP split config before transcoder */
 	intel_audio_sdp_split_update(crtc_state);
 
+	/* 128b/132b SST */
+	if (!is_hdmi && intel_dp_is_uhbr(crtc_state)) {
+		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+
+		intel_ddi_clear_act_sent(encoder, crtc_state);
+
+		intel_de_rmw(display, TRANS_DDI_FUNC_CTL(display, cpu_transcoder), 0,
+			     TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
+
+		intel_ddi_wait_for_act_sent(encoder, crtc_state);
+		drm_dp_dpcd_poll_act_handled(&intel_dp->aux, 0);
+	}
+
 	intel_enable_transcoder(crtc_state);
 
 	intel_ddi_wait_for_fec_status(encoder, crtc_state, true);