The idea that ctg uses different HPD live state bits is
total nonsense, at least on my machine (Dell Latitude
E5400).

The only reason DP-B even works on my ctg is that DP-D
live state is stuck high, even though there is no physical
DP-D port. So when the detect checks DP-B live state it
sees the stuck live state of DP-D instead. If I hack
the driver to not register DP-D at all, and thus we never
enabe DP-D HPD, DP-B stops working as well.

Just to put some conclusive evidence into this mess,
here are the actual hotplug register values for each port:
 Everything disconnected:
                    PORT_HOTPLUG_EN (0x00061110): 0x00000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
                    PORT_HOTPLUG_EN (0x00061110): 0x08000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x08000000
                    PORT_HOTPLUG_EN (0x00061110): 0x10000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
                    PORT_HOTPLUG_EN (0x00061110): 0x20000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
 Only port B connected:
                    PORT_HOTPLUG_EN (0x00061110): 0x00000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
                    PORT_HOTPLUG_EN (0x00061110): 0x08000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x08000000
                    PORT_HOTPLUG_EN (0x00061110): 0x10000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
                    PORT_HOTPLUG_EN (0x00061110): 0x20000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x20000000
 Only port C connected:
                    PORT_HOTPLUG_EN (0x00061110): 0x00000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000
                    PORT_HOTPLUG_EN (0x00061110): 0x08000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x08000000
                    PORT_HOTPLUG_EN (0x00061110): 0x10000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x10000000
                    PORT_HOTPLUG_EN (0x00061110): 0x20000000
                  PORT_HOTPLUG_STAT (0x00061114): 0x00000000

So the enable bit and live state bit always match 1:1.
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230302161013.29213-4-ville.syrjala@linux.intel.com