[Tinkerphones] MIPS CREATOR CI20

[Paul Boddie]

On Monday 25. March 2019 09.04.06 H. Nikolaus Schaller wrote:
> Hi,
> as you may know I am working a little on the PVR/SGX drivers for
> omap.
> 
> Since the latest DDK code (1.14) includes some jz4780 support,
> I researched and found that
> a) this is for the CI20 creator board
> b) it could also be used as an SGX reference implementation
>    https://elinux.org/CI20_upstream
>    https://elinux.org/CI20-SGX_kernel_module
> c) the CI20 is still available at not too high cost (<100€)
> d) LetuxOS already has some basic MIPS/jz4730 support (untested)
> 
> Does anyone have experimented with the CI20?

Yes, I have a CI20 board. I have used it for exploration with L4Re/Fiasco.OC, 
which needed some adjustment to work on the CI20 and which led to my efforts 
to get that software working on the Ben NanoNote and Letux 400 (of which you 
are familiar):

http://www.boddie.org.uk/paul/Landfall.html

Apart from that, I have used the Debian GNU/Linux distribution on the CI20, 
but since I don't care about the GPU (and don't like proprietary 
drivers/firmware), I haven't used it with the GPU enabled. On some occasions, 
I have used it as a desktop system, but more often I log into it across the 
network.

> Yes, I know that there will be no new products based on it,
> but we are tinkering... And tinkering with the CI20 may
> help to better understand the omap3/4/5 sgx drivers and
> separate the architecture and SoC dependent from the independent
> parts.

Indeed, I mentioned this in a thread about the PowerVR GPU in the CI20 only 
the other day, referencing your project:

https://groups.google.com/d/msg/mips-creator-ci20/5G_6rv0uixg/ZsxJUyC8BgAJ

Also, there was an update about the availability which I added to the 
elinux.org page:

https://www.elinux.org/CI20_Availability

The base system should already include the relevant drivers, but I only booted 
it once and discovered that it wouldn't produce a display on my monitor (via a 
HDMI-to-DVI cable) because the resolution was not set to a reasonable default.

I then used a later kernel (3.18 instead of 3.08) for which the supplied GPU 
drivers probably wouldn't work, anyway, and I didn't fetch newer ones. Of 
course, Imagination have dropped the CI20 completely, so the links on 
elinux.org do not work (as you probably saw already):

https://www.elinux.org/CI20-SGX_kernel_module

But I imagine that the objective would be to work from other sources, anyway. 
(My own priorities for L4Re involve enabling HDMI and the framebuffer, with 
the former being awkward because I would need to adapt Linux driver code since 
the HDMI stuff is not documented.)

I don't know what the situation is regarding newer kernels. There are all 
sorts of Android kernels that appear to be later than 3.18 (assuming that the 
versioning is consistent), and someone is maintaining Gentoo with newer "patch 
releases" of 3.18:

https://groups.google.com/d/topic/mips-creator-ci20/KslB5LFqd-s/discussion
https://www.setphaserstostun.org/pages/mips-creator-ci20-gentoo-resources/

The most recent kernels have dropped support for the flash memory used by the 
CI20, leading to recriminations:

https://groups.google.com/d/topic/mips-creator-ci20-dev/tVuJlzX_q0w/discussion

I tend to use SD cards for new installations, however, leaving the flash 
memory alone.

Paul