[Intel-gfx] [PATCH 0/4] Fix handling of DP bridge devices

[Adam Jackson]

Connection sense for DP bridge devices (like DP->VGA) currently only looks
at DPCD presence.  This is wrong.  However we would still like to avoid
DDC reads if possible, since they're much slower than AUXCH.

This series enhances i915 DP detection to know about branch devices, and
attempts to discover downstream port status and reflect that back to KMS.
It does not handle the case of multiple downstream ports very well, but
then neither does the existing code; if anyone has an example of such a
device I'll be happy to investigate.

- ajax