AMD Has DP MST DSC Support Ready For The Linux 5.6 Kernel

In addition to their AMDGPU/AMDKFD feature updates sent out on Thursday, AMD also sent in a special pull request to DRM-Next on its own of a new feature: DP MST DSC.

DP MST DSC is DisplayPort Multi-Stream Transport Display Stream Compression. AMD and the other common Linux display drivers have long supported DP MST for driving multiple displays off a single DisplayPort cable thanks to this specification. DP MST has been around since DisplayPort 1.2 and allows multiple independent displays to be served off a single DP port thanks to multiplexing the streams. MST also supports daisy-chaining and other convenient features. What's new now is supporting DSC (Display Stream Compression) for MST.

DSC itself is the VESA-backed low-latency compression algorithm for serving higher resolution content on reduced bandwidth. DSC is important for 8K and above outputs in particular or 4K@120Hz. DSC with MST becomes all the more important due to sharing a single cable for multiple displays, thus opening up setups to higher resolutions / higher refresh rates.

MST hubs and other devices do need to support DSC for this to work out, besides this new kernel support.

This pull request plumbs DSC into the core Direct Rendering Manager subsystem and ultimately exposes it for operation with the AMDGPU DRM driver.