[PATCH v2 1/5] drm/i915/ptl/dp_mst: Fix slave transcoder enabling wrt. DDI function

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

On PTL during modeset enabling configure the DDI function without
enabling it for MST slave transcoders before programming the data and
link M/N values. The DDI function gets enabled separately later in the
transcoder enabling sequence.

This fixes a slave transcoder getting stuck during enabling, leading
to page flip timeout errors on the corresponding pipe.

The spec requires the same programming step for ADLP+ platforms, that
will be addressed separately (on those platforms the above transcoder
getting stuck issue was not observed).

Bspec: 68849
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c    | 2 +-
 drivers/gpu/drm/i915/display/intel_ddi.h    | 2 ++
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 3 +++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 2bd14e2134be9..069cca4b38b2e 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -619,7 +619,7 @@ void intel_ddi_enable_transcoder_func(struct intel_encoder *encoder,
  * Same as intel_ddi_enable_transcoder_func(), but it does not set the enable
  * bit.
  */
-static void
+void
 intel_ddi_config_transcoder_func(struct intel_encoder *encoder,
 				 const struct intel_crtc_state *crtc_state)
 {
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.h b/drivers/gpu/drm/i915/display/intel_ddi.h
index 6d85422bdefef..1aa2e3a190aee 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.h
+++ b/drivers/gpu/drm/i915/display/intel_ddi.h
@@ -57,6 +57,8 @@ void intel_wait_ddi_buf_idle(struct drm_i915_private *dev_priv,
 void intel_ddi_init(struct intel_display *display,
 		    const struct intel_bios_encoder_data *devdata);
 bool intel_ddi_get_hw_state(struct intel_encoder *encoder, enum pipe *pipe);
+void intel_ddi_config_transcoder_func(struct intel_encoder *encoder,
+				      const struct intel_crtc_state *crtc_state);
 void intel_ddi_enable_transcoder_func(struct intel_encoder *encoder,
 				      const struct intel_crtc_state *crtc_state);
 void intel_ddi_disable_transcoder_func(const struct intel_crtc_state *crtc_state);
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 1a2ff3e1cb68f..7c16406883594 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -1224,6 +1224,9 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
 	if (DISPLAY_VER(dev_priv) < 12 || !first_mst_stream)
 		intel_ddi_enable_transcoder_clock(encoder, pipe_config);
 
+	if (DISPLAY_VER(dev_priv) >= 30 && !first_mst_stream)
+		intel_ddi_config_transcoder_func(encoder, pipe_config);
+
 	intel_dsc_dp_pps_write(&dig_port->base, pipe_config);
 	intel_ddi_set_dp_msa(pipe_config, conn_state);
 }
-- 
2.44.2