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
