After a busy Linaro Connect YVR, now it is the time to provide some update on my recent work towards upstreaming the Rock960 board from Vamrs Limited. This is the 4th board for me to do the upstreaming activity but this one lies close to my heart. To know the reason, please read below ;-)
Rock960 - Why so much love?
We at 96Boards treat all of our boards equally. But the board which gets more vendor support seems to be popular all the time. And this Rock960 is one among them. Before going further, let me give a short introduction to this board. Rock960 is a Consumer Edition board based on the Rockchip’s popular RK3399 (Armv8 dual-core Cortex-A72 and quad-core Cortex-A53) SoC. Even though the board complies to the 96Boards CE standard, it has some notable features like M.2 PCI-E (Key M) connector, External Debug port, Type C OTG port etc…
More love towards Rock960 comes from the fact that the SoC is well supported in most of the OpenSource projects such as Arm Trusted Firmware, U-Boot, Linux Kernel (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git), Yocto etc… This makes the life easy for us to support/promote the board. Also, the board vendor Vamrs has put in a lot of efforts to provide the board documentation, user guides, and all bits and pieces necessary to get started with the board, which is very commendable in my opinion.
So, the above factors make the board more popular among the community and we are so happy to see that :)
Since I said that the SoC is already well supported in OS projects, my focus was only on getting the board support merged. So, I started with Linux kernel first. While looking into the existing supported boards based on RK3399, I came to know that the Ficus 96Boards Enterprise board was already upstreamed by folks from Collabora.
Since both Ficus and Rock960 comes from Vamrs, they share the common design and are more similar with base functionalities. So, after discussing with the Ficus board maintainer, I decided to create a common devicetree include for the Rock960 family and individual board DTS files for Rock960 and Ficus.
It should be noted that in Linux kernel and U-boot, we only need to add a devicetree file for adding a board support. This is the major benefit of using devicetree for hardware representation. So, after sorting out the common nodes, I pushed out the below patches for adding Rock960 board and adapting Ficus to the common Rock960 board family.
The patchset received some quick response from the maintainer and after 3 iterations, all patches got applied to the Rockchip maintainer’s tree for 4.20. This was quick :)
Then comes the U-Boot support. Here Ficus board support patches were just submitted and not yet merged into the tree. So after discussion, I took the patches and adapted it based on the common Rock960 family as per Linux kernel. Finally, I submitted those patches and it is in 4th iteration now.
I should mention that the U-Boot support was somewhat challenging when compared to Linux kernel. The reason was, U-Boot has the DRAM initialization part when built as SPL and that varies between Rock960 and Ficus.
Rock960 has the LPDDR3 memory while Ficus has the DDR3 memory. Luckily for Ficus, the DRAM configuration was already present in u-boot, so we used it. But for Rock960, I have to add the DRAM configuration and that took some time.
Finally, we were able to upstream Rock960 in Linux kernel and U-Boot is also so close. Here we leveraged the SoC support in both projects and that really helped us… Kudos to Rockchip folks :D
But I should thank the timely help from below people in the community for making the upstream activity smooth and quick.
- Ezequiel Garcia - Ficus board maintainer
- Peter Robinson - Redhat Fellow
- Heiko Stubner - Rockchip maintainer in Linux Kernel
Soon we should be able to see Fedora #29 booting with the mainline kernel/u-boot on Rock960. Stay tuned for next part :)