[Letux-kernel] [OpenOCD-devel] [PATCH]: d86217d board: add Skytone Alpha 400

[Riccardo Mottola]

Hi alll!

I still have my Letux 400 and it works, even the battery hold some 
charge... possibly because I use it rarely, but still do test it every 
month or so. Before the CI20 it was absolutely the only MIPS-LE setup I 
had (who much I wish it would be BE).


Paul Boddie wrote:
>
>> I have CCed the list plus two GNUsteppers from whom I know that they
>> are still interested in MIPS and this machine.
> Nice to know that some people are still interested in MIPS. Probably more so
> than the company that owns the technology these days. ;-)

Yes... MIPS is in bad waters.... so sad. also the CI20 proves the JZ 
chinese processors are very capable and compare well.
The cpu of the Letux400 is a bit hampered by the lack of the FPU 
requiring a recompile - the original distribution from HongKong was 
optimized for that and run fast - including a mini-Firefox and MP3 
playback working, instead on Debian which requires hard-float and 
emulation is used, performances are bad, you cannot even an audio file. 
But of course, we have all ready packages :)
Remembers me the day of 68k Macs and Amigas which had no FPU ("embeded 
controller" or "low cost" CPUs...)

>
>>> Am 24.10.2020 um 15:35 schrieb Lubomir Rintel <lkundrak at v3.sk>:
>>>
>>> I've only recently got the machine and started to look around. I'd like
>>> it to eventually run up to date software, notably mainline Linux.
>>> I'm currently beating u-boot into shape and intend to try send out the
>>> patches upstream soonish.
>>>
>>> I've noticed that H. Nikolaus Schaller keeps rebasing his and Paul
>>> Boddie's jz4730 patches in the letux-kernel tree [1].
>> We try to do our best...
> Indeed.

Promising!!!

>
>>> I've had to fix up quite some issues to get the thing to build so I
>>> suspect they probably don't run it?
>> Well, it is unfortunately on really low priority for me. I just would have
>> to open my Letux 400 and solder a connector for the serial console and close
>> the device again :) So that I can see what is happening during hand-over
>> from U-Boot to the kernel or if the kernel isn't booting to at least some
>> login: prompt.
> My patches are rather tentative because (1) a lot of the work has been to just
> get things updated to work with "modern" practices, and (2) I have low
> expectations about things working until most of the pieces are in place. And
> even then, I have fairly low expectations because the Linux kernel isn't
> exactly the most testable thing, especially without a serial console.

It would be nice to test - given compared to the CI20 the board though 
and the difficulty of JTAG or console, support for internal network and 
framebuffer is important.

>> Another problem is that I am no longer experienced in the details how to
>> boot from SD card... AFAIR there was some special key combination and if
>> one get it wrong the system will overwrite flash where only JTAG could
>> recover the bricked device.
> "Fn" and left "Shift" should boot from SD. I was using that to boot my L4Re
> payloads and didn't have any problems. That applies to the Letux 400, however,
> and I can't make any guarantees about other variants.

I am "weary" because there was also a combination of keys which copied 
the kernel from the SD card to the internal flash... potentially causing 
issues.

I'd be interested to try things! Currently I have a weird setup with a 
sandbox into debian but still running the old stock kernel (boot on the 
original kernel and OS, then "switch" to debian). It is still a 2.x 
series kernel

>> A minor problem is that the remaining batteries are now all broken, but it
>> works without, just with power supply.
> Batteries are a real problem. I also have an Efika Smartbook whose battery no
> longer works. The lifespan and lifecycle of batteries should be a real
> concern, but everything seems to be "designed for disposal" regardless of how
> much or often it ends up being used.
>
>>> My intent was to send the patches their way and ask about
>>> the status of the tree; adding them to Cc now so they can chime in.
>> Yes, please. Patches are always welcome!
>>
>>> [1] https://git.goldelico.com/?p=letux-kernel.git;a=heads
>>>
>>>> I found a few years ago that the FCC registration document for the
>>>> Skytone Alpha 400 (FCC ID WMGALPHA400) simply points to the Sungworld
>>>> SW-E700 (FCC ID WI3SW-E700). The Sungworld FCC database entry has a
>>>> schematic attached.
>>> I've got the schematic from here [2]. It looks like it's probably the
>>> same one.
>>>
>>>
>>> [2] https://download.goldelico.com/letux-400/files/
>> Hardware-wise these devices (Skytone, Elonex, Letux and many more) seem
>> to be the same.
> Let's not forget the documentation area, too:
>
> https://projects.goldelico.com/p/letux400/doc/
>
> I could probably add more details to that, given that there has been some
> effort to formulate how the hardware works in connection with modernising
> those patches.

Please do!

Riccardo