At present, AMD’s PTDMA driver for Linux has been updated to version v10, hoping to eventually merge into the Linux mainline.
PTDMA is a Linux driver released by AMD in September 2019 to support the Pass-Through DMA controller of the EPYC processor and allow high-bandwidth memory-to-memory and I/O copy operations. In addition, the PTDMA controller and driver are optimized for use with AMD non-transparent bridge (NTB) devices.
After the initial patch series, the AMD PTDMA Linux driver quickly passed several rounds of review in the following months. However, it spent a lot of time in subsequent revisions and patch submissions. Up to now, it is the tenth revision. This revision includes removing unnecessary printing and variables, removing unused pt_debugfs_lock from the debufs code, and maintaining the same file permissions for all debug directories, etc.
In the next few weeks, the driver will continue to be reviewed to determine whether it can be incorporated into the Linux kernel mainline.