drm/i915/dp_mst: Recompute all MST link CRTCs if DSC gets enabled on the link

drm/i915/dp_mst: Recompute all MST link CRTCs if DSC gets enabled on the link

The state of all the CRTCs on an MST link must be recomputed, if DSC
gets enabled on any of the CRTCs on the link. For instance an MST
docking station's Panel Replay capability may depend on whether DSC is
enabled on any of the dock's streams (aka CRTCs). To assist the Panel
Replay state computation for a CRTC based on the above, track in the
CRTC state if DSC is enabled on any CRTC on an MST link.

The intel_link_bw_limits::force_fec_pipes mask is used for a reason
similar to the above: enable FEC on all CRTCs of a non-UHBR (8b10b) MST
link if DSC is enabled on any of the link's CRTCs. The FEC enabled state
for a CRTC doesn't indicate if DSC is enabled on a UHBR MST link (FEC is
always enabled by the HW for UHBR, hence it's not tracked by the
intel_crtc_state::fec_enable flag for such links, where this flag is
always false).

Based on the above, to be able to determine the DSC state on both
non-UHBR and UHBR MST links, track the more generic DSC-enabled-on-link
state (instead of the FEC-enabled-on-link state) for each CRTC in
intel_link_bw_limits.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20251015161934.262108-7-imre.deak@intel.com