[Lenny400] jz47xx Device Tree

Dr. H. Nikolaus Schaller hns at goldelico.com
Sun Apr 5 19:24:11 CEST 2015


After doing some more research, I think the status of MIPS DT is even more advanced than I had thought:

1. 4.0-rc already supports a handful of DT based MIPS CPUs:
	https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/mips/boot/dts?id=refs/tags/v4.0-rc6

2. there are patches circulating on LKML to convert jz4740 to DT:
	https://lkml.org/lkml/2015/2/4/392

	unfortunately they did end up - as far as I can see - in a social issue (within imgtec?)
	https://lkml.org/lkml/2015/2/4/463

	There has been some more activity here:
	https://patchwork.kernel.org/project/LKML/list/?q=jz4780

	Some of these patches have already appeared in linux-next (so they will become part of 4.1-rc1 in ca. 4 weeks):
	https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/log/?id=refs%2Ftags%2Fnext-20150402&qt=grep&q=jz4740

	Driver for his activity is the JZ4780 CI20 board: http://www.elinux.org/CI20_upstream
	e.g. https://github.com/MIPS/CI20_linux/blob/ci20-v3.18/arch/mips/boot/dts/jz4740.dtsi

	The really good thing is that this is done more or less officially by Imgtec - so there is manpower behind.

Since we now know that the jz4730 also has some similarities as well, we should IMHO try to help to get the
jz4740 DT patches upstream. Instead of tweaking the non-DT jz4740 code and #include like Paul’s patch does .
Which might then lead soon (3-6 months?) to merge conflicts with linus/master.

And just add our own jz4730.dtsi and jz4730-minipc.dts and some jz4730 specific drivers.

Seems to be easier and future-proof for me than starting to work on any non-DT code.

But we should definitively use Paul’s patch as the basis for understanding what we have to change from jz4740 to jz4730.

What do you think?

BR,
Nikolaus



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