drm/i915: Allow bigjoiner for MST

We need bigjoiner support with MST functionality
for MST monitor resolutions > 5K to work.
Adding support for the same.

v2: Addressed review comments from Jani.
Revert rejection of MST bigjoiner modes and add
functionality

v3: Fixed pipe_mismatch WARN for mst_master_transcoder
Credits-to: Manasi Navare <[email protected]>

v4: Utilize intel_crtc_joined_pipe_mask() also for handling
    bigjoiner slave pipes for MST case(Stan)
[v5: vsyrjala: chunked the modeset squence stuff out,
               removed bogus mst master transcoder hack,
	       keep mgr_lock near the full_pbn check]
[v6: vsyrjala: Calculate DSC slices correctly for bigjoiner (Imre)]

Reviewed-by: Manasi Navare <[email protected]>
Reviewed-by: Arun R Murthy <[email protected]>
Signed-off-by: Vidya Srinivas <[email protected]>
Co-developed-by: Ville Syrjälä <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: vsrini4

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

@@ -88,11 +88,10 @@ static int intel_dp_mst_bw_overhead(const struct intel_crtc_state *crtc_state,
 
 	if (dsc) {
 		flags |= DRM_DP_BW_OVERHEAD_DSC;
-		/* TODO: add support for bigjoiner */
 		dsc_slice_count = intel_dp_dsc_get_slice_count(connector,
 							       adjusted_mode->clock,
 							       adjusted_mode->hdisplay,
-							       false);
+							       crtc_state->bigjoiner_pipes);
 	}
 
 	overhead = drm_dp_bw_overhead(crtc_state->lane_count,
@@ -525,6 +524,7 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_atomic_state *state = to_intel_atomic_state(conn_state->state);
+	struct intel_crtc *crtc = to_intel_crtc(pipe_config->uapi.crtc);
 	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
 	struct intel_dp *intel_dp = &intel_mst->primary->dp;
 	struct intel_connector *connector =
@@ -542,6 +542,11 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
 		return -EINVAL;
 
+	if (intel_dp_need_bigjoiner(intel_dp, connector,
+				    adjusted_mode->crtc_hdisplay,
+				    adjusted_mode->crtc_clock))
+		pipe_config->bigjoiner_pipes = GENMASK(crtc->pipe + 1, crtc->pipe);
+
 	pipe_config->sink_format = INTEL_OUTPUT_FORMAT_RGB;
 	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
 	pipe_config->has_pch_encoder = false;
@@ -1376,10 +1381,6 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 					       max_link_clock, max_lanes);
 	mode_rate = intel_dp_link_required(mode->clock, min_bpp);
 
-	ret = drm_modeset_lock(&mgr->base.lock, ctx);
-	if (ret)
-		return ret;
-
 	/*
 	 * TODO:
 	 * - Also check if compression would allow for the mode
@@ -1392,17 +1393,18 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 	 *   corresponding link capabilities of the sink) in case the
 	 *   stream is uncompressed for it by the last branch device.
 	 */
-	if (mode_rate > max_rate || mode->clock > max_dotclk ||
-	    drm_dp_calc_pbn_mode(mode->clock, min_bpp << 4) > port->full_pbn) {
-		*status = MODE_CLOCK_HIGH;
-		return 0;
-	}
 	if (intel_dp_need_bigjoiner(intel_dp, intel_connector,
 				    mode->hdisplay, target_clock)) {
 		bigjoiner = true;
 		max_dotclk *= 2;
+	}
+
+	ret = drm_modeset_lock(&mgr->base.lock, ctx);
+	if (ret)
+		return ret;
 
-		/* TODO: add support for bigjoiner */
+	if (mode_rate > max_rate || mode->clock > max_dotclk ||
+	    drm_dp_calc_pbn_mode(mode->clock, min_bpp << 4) > port->full_pbn) {
 		*status = MODE_CLOCK_HIGH;
 		return 0;
 	}
@@ -1445,7 +1447,7 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 		return 0;
 	}
 
-	*status = intel_mode_valid_max_plane_size(dev_priv, mode, false);
+	*status = intel_mode_valid_max_plane_size(dev_priv, mode, bigjoiner);
 	return 0;
 }