Based on a recent BSpec update (Index/21750) we must handle the TCCOLD event associated with the DP-alt mode. We can detect this event by reading an invalid all-1s value from FIA registers. After detecting TCCOLD we will: - fall back to TBT-alt mode when attempting to switch to DP-alt mode - conclude that nothing is connected during live status detection - WARN when already in unsafe mode, since then TCCOLD is unexpected v2: - Use DRM_DEBUG_KMS instead of DRM_DEBUG_DRIVER. (José) v3: - Use 0xffffffff instead of -1 as invalid FIA reg value. (José, Ville) - Check for TCCOLD in icl_tc_phy_status_complete() too. (Ville) Cc: José Roberto de Souza <jose.souza@intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: José Roberto de Souza <jose.souza@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-12-imre.deak@intel.com