drm/i915/dp: Enable DSC via the connector decompression AUX

Enable DSC using the DSC AUX device stored for this purpose in the
connector. For clarity add separate functions to enable/disable the
decompression, since these sequences will diverge more in follow-up
patches that also enable/disable DSC passthrough and on MST do the
actual enabling/disabling only for the first/last user of the given
AUX device. As a preparation for the latter refcounting change, also
pass the atomic state to the functions.

While at it set/clear only the DP_DECOMPRESSION_EN flag in the
DP_DSC_ENABLE DPCD register, preserving the reserved register bits.

Besides preserving the reserved register bits, the behavior stays as
before, as DSC is still only enabled for the first MST stream (which a
follow-up patch changes, enabling it for all streams).

v2:
- Add a helper function setting/clearing the decompression flag,
  preserving the reserved register bits.
v3:
- Add separate functions to enable/disable decompression and pass the
  atomic state to these.
- Add DocBook for both functions.

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> (v2)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030155843.2251023-24-imre.deak@intel.com

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index cc2a38fc22d0d..6cec72ac6422e 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -2539,7 +2539,9 @@ static void mtl_ddi_pre_enable_dp(struct intel_atomic_state *state,
 
 	intel_dp_configure_protocol_converter(intel_dp, crtc_state);
 	if (!is_mst)
-		intel_dp_sink_set_decompression_state(intel_dp, crtc_state, true);
+		intel_dp_sink_enable_decompression(state,
+						   to_intel_connector(conn_state->connector),
+						   crtc_state);
 
 	/*
 	 * DDI FEC: "anticipates enabling FEC encoding sets the FEC_READY bit
@@ -2692,7 +2694,9 @@ static void tgl_ddi_pre_enable_dp(struct intel_atomic_state *state,
 
 	intel_dp_configure_protocol_converter(intel_dp, crtc_state);
 	if (!is_mst)
-		intel_dp_sink_set_decompression_state(intel_dp, crtc_state, true);
+		intel_dp_sink_enable_decompression(state,
+						   to_intel_connector(conn_state->connector),
+						   crtc_state);
 	/*
 	 * DDI FEC: "anticipates enabling FEC encoding sets the FEC_READY bit
 	 * in the FEC_CONFIGURATION register to 1 before initiating link
@@ -2773,8 +2777,9 @@ static void hsw_ddi_pre_enable_dp(struct intel_atomic_state *state,
 		intel_dp_set_power(intel_dp, DP_SET_POWER_D0);
 	intel_dp_configure_protocol_converter(intel_dp, crtc_state);
 	if (!is_mst)
-		intel_dp_sink_set_decompression_state(intel_dp, crtc_state,
-						      true);
+		intel_dp_sink_enable_decompression(state,
+						   to_intel_connector(conn_state->connector),
+						   crtc_state);
 	intel_dp_sink_set_fec_ready(intel_dp, crtc_state, true);
 	intel_dp_start_link_train(intel_dp, crtc_state);
 	if ((port != PORT_A || DISPLAY_VER(dev_priv) >= 9) &&
@@ -3360,6 +3365,8 @@ static void intel_disable_ddi_dp(struct intel_atomic_state *state,
 				 const struct drm_connector_state *old_conn_state)
 {
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	struct intel_connector *connector =
+		to_intel_connector(old_conn_state->connector);
 
 	intel_dp->link_trained = false;
 
@@ -3368,8 +3375,8 @@ static void intel_disable_ddi_dp(struct intel_atomic_state *state,
 	intel_psr_disable(intel_dp, old_crtc_state);
 	intel_edp_backlight_off(old_conn_state);
 	/* Disable the decompression in DP Sink */
-	intel_dp_sink_set_decompression_state(intel_dp, old_crtc_state,
-					      false);
+	intel_dp_sink_disable_decompression(state,
+					    connector, old_crtc_state);
 	/* Disable Ignore_MSA bit in DP Sink */
 	intel_dp_sink_set_msa_timing_par_ignore_state(intel_dp, old_crtc_state,
 						      false);