Tuesday 11 August Yureka Lilian sent to Linux kernel mailing list a set of two patches that adds support NVMe for the SoC Apple M4internally identified as T8132. The first patch introduces the apple compatible,t8132-nvme-ans2 in the dt-bindings, the second brings support into the driver. The object of the intervention is theANS2the same NVMe variant already present on Apple SoCs from M1 to M3.
The variant fitted to the M4 uses a separate MMIO base for your NVMMU and requires that I/O queues be registered with a additional MMIO writing. Otherwise, Lilian writes in the cover letter, the block is “largely the same as the ANS2 NVMe variants found on Apple SoCs M1 to M3.” The row count confirms this: drivers/nvme/host/apple.c change to 41 linesthe bindings file in 77, for a total of 84 additions and 34 removals on the two files.
However, the series does not apply alone. The trailers generated by b4 indicate, in addition to the basic commit, six preliminary patches belonging to a previous series on the NVMe firmware ABI, which must be lined up before these two. The input of the M4 support therefore also depends on the progress of that upstream work.
M4 SoCs are not supported by the mainline Linux kernel, nor is the M3 series hardware ready for use by end users today. The NVMe work is one of the first elements of M4 support to take shape, while the rest of the port is still to be built. It will likely be a long time before an M4 machine is usable on a daily basis under Linux, let alone full upstream support.
The first response on the list came about an hour after posting, from Rob Herring; the next day he intervened Krzysztof Kozlowskiand Lilian replied the same morning. Both are among the devicetree recipients indicated in the series. Thread counts for now eight messagescover letter and patches included.
