drm/i915/display: Panel Replay BW optimization for DP2.0 tunneling

drm/i915/display: Panel Replay BW optimization for DP2.0 tunneling

Unused bandwidth can be used by external display agents for Panel Replay
enabled DP panel during idleness with link on. Enable source to replace
dummy data from the display with data from another agent by programming
TRANS_DP2_CTL [Panel Replay Tunneling Enable].

v2:
- Enable pr bw optimization along with panel replay enable. [Jani]

v3:
- Write TRANS_DP2_CTL once for both bw optimization and panel replay
enable. [Jani]

v4:
- Read DPCD once in init() and store in panel_replay_caps. [Jouni]

v5:
- Avoid reading DPCD for edp. [Jouni]
- Use drm_dp_dpcd_read_byte() and some cosmetic changes. [Jani]

v6:
- Extend the corresponding interface defined in drm_dp_tunnel.c
to query the Panel Replay optimization capability. [Imre]

v7:
- Clear TRANS_DP2_PR_TUNNELING_ENABLE if pr bw optimization
is not allowed. [Jouni]
- Move intel_dp_is_edp() check. [Jouni]

Bspec: 68920
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patch.msgid.link/20260330133620.3750559-4-animesh.manna@intel.com