Intel Linux Driver Getting Skylake/Gen9 Port Sync To Fix 5K Tiled Display Issues

A four year old Intel Linux display driver bug around corruption issues when trying to drive tiled displays (namely 5K+ setups with dual DisplayPort connections) on Intel "Gen9" graphics hardware for Skylake up until Icelake could soon be marked as resolved.

Longtime Intel Linux developer Ville Syrjala sent out a set of 13 patches today for adding port synchronization support for Skylake+ (Gen9). Intel developers have port sync already in place and working for Icelake/Gen11 hardware while for years this capability has been missing from Gen9 although supported by the hardware itself.

Port sync is needed for ensuring the synchronized outputs on tiled display setups, namely the growing number of displays beyond 4K that require two DisplayPort cables. Going back to 2016 has been bug reports over 5K tiled display issues with Gen9 hardware.

Running Windows works correctly with Intel's driver there or using a single DisplayPort cable at a lower resolution works fine on such displays. Thanks now to these new patches for port sync the behavior should be correct on Linux with Gen9. This Gitlab ticket outlines how the display can look up to now on Linux with two DP connections:

The patches are now out there for review. Though given the timing and the DRM-Next cutoff quickly approaching, either this will come in late for Linux 5.7 or be diverted to Linux 5.8 assuming all goes well punctually with the review.