The ‘linux-next’ kernel branch has included the meson/gxbb mmc driver for some time, but the boot process hung on root disk access.     I tested with the latest (November 17) version, and this time, the boot process completed successfully:

Fedora 25 (Workstation Edition)
Kernel 4.9.0-rc5-next-20161117-c2 on an aarch64 (ttyAML0)

The only patch I applied was the meson_ethernet_tx one (see previous article – http://rglinuxtech.com/?p=1844), as this fix is still work-in-progress..

This time, usb gave a tombstone during the boot process, but lsusb actually showed the root hubs, although no connected devices were recognised:

# lsusb
Bus 001 Device 002: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The development of C2 support on u-boot and the kernel itself has been somewhat spasmodic, as there were supporting patches for u-boot months ago, but for some reason these were never accepted, and the mmc kernel driver was completely re-written..    I would speculate that ‘full’ support – in u-boot and the mainline kernel – will probably be achieved by the time the 4.10 kernel is released..

Robert Gadsdon.   November 17, 2016.