[PATCH v2 20/34] drm/i915/dp_mst: Use link caps for non-DSC config selection

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

Use the link caps helper to select the maximum MST link configuration
for non-DSC computation, instead of using the separate max rate and lane
count limits, which may not form a valid configuration after individual
configs are disabled by fallback.

This is a step towards unifying configuration selection and iteration
across connector types and between compute and fallback paths.

In some cases all configurations should be considered, as noted in the
code comment; for now keep the existing behavior of selecting the
maximum bandwidth configuration as determined by the MST connector's BW
config iteration order.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index e113c9e60e67d..47b8563f85e4d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -445,8 +445,20 @@ static int mst_stream_compute_link_config(struct intel_dp *intel_dp,
 					  struct drm_connector_state *conn_state,
 					  const struct link_config_limits *limits)
 {
-	crtc_state->lane_count = limits->max_lane_count;
-	crtc_state->port_clock = limits->max_rate;
+	struct intel_connector *connector = to_intel_connector(conn_state->connector);
+	struct intel_dp_link_config max_link_config;
+
+	/*
+	 * FIXME: Use a proper iteration over the link configurations, instead
+	 * of using only the max BW config. For instance UHBR rate configs may
+	 * have additional limitations over non-UHBR ones, due to the DSC DPT
+	 * bpp maximum limit.
+	 */
+	if (!intel_dp_get_connector_max_link_config(connector, limits, &max_link_config))
+		return -EINVAL;
+
+	crtc_state->port_clock = max_link_config.rate;
+	crtc_state->lane_count = max_link_config.lane_count;
 
 	/*
 	 * FIXME: allocate the BW according to link_bpp, which in the case of
-- 
2.49.1