rock960c

[Peter Robinson]

On Tue, Jul 6, 2021 at 8:03 AM Trevor Woerner <twoerner at gmail.com> wrote:
>
> Hi,
>
> I was hoping that one day support would be added for the rockchip rock960c
> board (from the 96boards series, https://www.96boards.org/product/rock960c/).
> NOTE: this board is different from the rock960 board (aka rock960 a/b) that is
> currently supported.
>
> Schematics and datasheets aren't easy to come by. A while back someone
> mentioned that the only difference between the rock960 a/b and the rock960c is
> that the rock960c uses different SDRAM (LPDDR4 instead of LPDDR3). Searching
> around on the Internet it would appear that the rock960c uses the same SDRAM
> as the rock-pi-4 devices (maybe?).

I don't think it has a USB-C port, nor a onboard eMMC, although from
memory it does have a header.

> The actual SDRAM on the board is H9HCNNN4KUML-HRNMN, but I can't find a
> datasheet for it anywhere, not even on Hynix's website.
>
> I tried creating a rock960c device by copying the rock960 things. The one
> change I made was that my rk3399-rock960c-u-boot.dtsi file has:
>
>         #include "rk3399-sdram-lpddr4-100.dtsi"
>
> (which is what the rock-pi-4 is using) instead of:
>
>         #include "rk3399-sdram-lpddr3-2GB-1600.dtsi"

You'll probably need to add/update a DDR line in the config file as well.

> (which is what rk3399-rock960-u-boot.dtsi is using). Unfortunately this
> doesn't succeed. The TPL is invoked, then there's nothing else on the console:
>
>         U-Boot TPL 2021.04 (Jun 30 2021 - 18:16:57)
>
> I then tried building and using the vendor-supplied u-boot fork for the
> rock960c which is found here:
>
>         git://github.com/96rocks/u-boot.git
>
> but it is quite old (U-Boot 2017.09) and pre-dates the TPL/idbloader things.
> If I understand things correctly, the vendor branch only builds u-boot and the
> spl, I then need to mash in some sort of binary ddr file to the spl to get a
> working first-stage bootloader (?). I'm unclear how to take the build output
> from the vendor branch and create a working bootloader to load on my sdcard
> (the only docs for the rk3399 in that branch are generic and don't refer to
> things that come out of the build for the rock960c).

I personally wouldn't waste your time with the vendor one, I would
think everything needed is already upstream for the core support.

> In any case, if anyone has any any tips etc I'd appreciate it :-)

There's not an upstream dts either, which probably isn't a big issue
for the basics. I don't remember whether or not if I have a revC of
these boards somewhere, I can't promise timing wise but if I get a
moment I'll see if I can work out if I have one.