Imagination's PowerVR DRM kernel driver and PowerVR Vulkan driver in Mesa has been seeing BXM-4-64 work for a while. Finally now the firmware for this GPU is upstream in linux-firmware.git as the missing piece for making a nice user experience story for those wanting to leverage this open-source GPU driver stack.
Frank Binns of Imagination describes the level of support for the PowerVR BXM-4-64 with the T-Head TH1520 SoC as being in good shape:
"Support for the BXM-4-64 GPU, as found in the Alibaba T-Head TH1520, has been available in the upstream Linux kernel for a while and is now in good shape. This adds the initial firmware to support it."
This commit landed the 131KB blob.
The T-Head TH1520 developed by Alibaba features a quad-core RISC-V CPU design (Xuantie C910) with the BXM-4-64 GPU. This is found in boards like the Lichee Pi4A and BeagleV Ahead.