drm/i915/dp: Fix determining SST/MST mode during MTP TU state computation

commit 732b87a409667a370b87955c518e5d004de740b5 upstream.

Determining the SST/MST mode during state computation must be done based
on the output type stored in the CRTC state, which in turn is set once
based on the modeset connector's SST vs. MST type and will not change as
long as the connector is using the CRTC. OTOH the MST mode indicated by
the given connector's intel_dp::is_mst flag can change independently of
the above output type, based on what sink is at any moment plugged to
the connector.

Fix the state computation accordingly.

Cc: Jani Nikula <jani.nikula@intel.com>
Fixes: f6971d7427c2 ("drm/i915/mst: adapt intel_dp_mtp_tu_compute_config() for 128b/132b SST")
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4607
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250507151953.251846-1-imre.deak@intel.com
(cherry picked from commit 0f45696ddb2b901fbf15cb8d2e89767be481d59f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
References: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14218
[Rebased on v6.14.8 and added References link. (Imre)]
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 86d6185fda50adcb8add7b127b8ad3505a14aef3..8a6135b179d3b9bf9687a4507f24d9d9b6f803e7 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -221,6 +221,7 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
                to_intel_connector(conn_state->connector);
        const struct drm_display_mode *adjusted_mode =
                &crtc_state->hw.adjusted_mode;
+       bool is_mst = intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST);
        fixed20_12 pbn_div;
        int bpp, slots = -EINVAL;
        int dsc_slice_count = 0;
@@ -271,7 +272,7 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
                                         link_bpp_x16,
                                         &crtc_state->dp_m_n);
 
-               if (intel_dp->is_mst) {
+               if (is_mst) {
                        int remote_bw_overhead;
                        int remote_tu;
                        fixed20_12 pbn;