drm/i915/dp_mst: Don't require DSC hblank quirk for a non-DSC compatible mode

If an MST branch device doesn't support DSC for a given mode, but the
MST link has enough BW for the mode, assume that the branch device does
support the mode using an uncompressed stream.

Fixes: 55eaef164174 ("drm/i915/dp_mst: Handle the Synaptics HBlank expansion quirk")
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241009110135.1216498-2-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 2822ae1..1a2ff3e 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -467,6 +467,9 @@ hblank_expansion_quirk_needs_dsc(const struct intel_connector *connector,
        if (mode_hblank_period_ns(adjusted_mode) > hblank_limit)
                return false;
 
+       if (!intel_dp_mst_dsc_get_slice_count(connector, crtc_state))
+               return false;
+
        return true;
 }