[Arm-netbook] ingenic jz4760 (600mhz, MIPS, X-Burst, 720p), FSF Hardware-Endorseable

[lkcl luke]

On Tue, Jan 3, 2012 at 2:24 PM, Gordan Bobic <gordan at bobich.net> wrote:
>  On Tue, 3 Jan 2012 13:55:04 +0000, lkcl luke <luke.leighton at gmail.com>
>  wrote:
>> On Tue, Jan 3, 2012 at 1:42 PM, Gordan Bobic <gordan at bobich.net>
>> wrote:
>>
>>
>>>  Can you elaborate how this VPU relates to the graphics subsystem on
>>> the
>>>  JZ4760?
>>
>>  there isn't one [a graphics subsystem].  ok, there is - it has some
>> 2D primitives.
>>
>>> What about the GPU itself? Is it little more than a dumb frame
>>>  buffer and fully open?
>>
>>  it's fully open.  and has some basic 2D stuff.  but effectively it's
>> a framebuffer.
>>
>>> I guess what I really want to know is whether it
>>>  is possible to maintain the standard separation of functionality,
>>> e.g. a
>>>  xorg driver with xv and gl acceleration? Is there such a driver
>>> already?
>>
>>  don't know.  probably not.  the potential of the jz4760 seems to
>> have
>> completely escaped the free software community: it's not hard to see
>> why - the CPU's pretty much only exclusively available in the PRC.
>
>  OK, so we have a basic 2D frame buffer, and enough bandwidth to the
>  video RAM to do things like xv and gl acceleration in software by using
>  the VPU. Sounds to me like there is plenty of scope of writing the
>  drivers that do the job in the traditional way. The app doesn't car if
>  it's the GPU doing the number crunching or whether the driver palms it
>  off on the vector math unit.

 precisely.

> As long as the standard APIs are exposed.
>  But - do such drivers exist?

 do a rethink - it's standard GNU/Linux software - you just recompile it.

>>  but, then again, the jz4740 i think it was ended up in the ben
>> nanonote, so it's not all bad.
>
>  Quick googling suggrests the Nanonote actually has a JZ4720, not
>  JZ4760.

 ahh ok :)

>>  the opengl library... ahh, that's a hilarious one.  the tools to do
>> the X-Burst acceleration assembly-instructions are basically ... get
>> this: an awk script!  so it goes hunting through c code
>> (pre-processor) and substitutes hard-coded assembly instructions in
>> the place of core blocks of c code!
>>
>>  unbelievable :)
>
>  Umm... That is indeed quite "special".
>
>>  so, in this way, it's using the _standard_ mesa gl source code...
>> just put through a pre-processor "wringer" which gives a little bit
>> of
>> extra oomph.  hilarious, but it works.
>
>
>  So this awk script makes an "accelerated" driver by taking the mesa
>  source and replaces parts the software GL renderer code matching a
>  specific pattern with VPU specific assemblies?

 yeah :)  a bit like... no, there's nothing like it really :)

>  Wow. I wonder how many orders of magnitude more we'd get out of it with
>  a proper compiler solution...

 yeah.  gcc with proper VPU support, like sparc's LEON4, and powerpc's
altivec optimisation, would give the whole CPU a face-lift because you
could compile the entire codebase with it, not just a few sections.


>  More to the point, I wonder how much else would benefit from this if it
>  were a proper compiler target.
>
>>>  How does this compare to the Allwinner A10 on cost
>>
>>  well it has to be less.  if you look on taobao.com at qty 1 pricing
>> you can find the CPU from random suppliers for 46RMB (£4.60) - but
>> that's one-off quantities!
>>
>>  what that means is that we could actually buy all the parts
>> *without*
>> having to go to Ingenic, design the board *without* having to go to
>> Ingenic (because they've already released all required information).
>
>  How does the performance compare to, say, the Marvell Armada that runs
>  at similar clock speeds?

 abbbsolutely no idea.

>  How much RAM can JZ4760 handle?

 i honestly don't know!  probably 512mb.

>  What interfaces does it have? USB? SATA? PCIe?

 USB2.  err... that's it :)  you don't get much for a 130nm (0.13
micron) completely china-home-grown CPU, gordan!

>>> and openness?
>>
>>  jz4760 beats the allwinner because allwinner haven't got everything
>> online already available and even if they did, there's still the MALI
>> 400MP to contend with.
>
>  Which begs the question of why we aren't doing that instead...

 i'm speaking to richard about promoting it _as well_.  the reason for
"as well" is because the allwinner has a better chance for mass-volume
purposes.  it's future-proofed.


>>>  What boards/devices are available with JZ4769?
>>
>>  4760 not 4769.
>
>  Sorry, fat finger error.
>
>>  you can get MIDs on taobao.com for 300RMB (£30).
>
>  Curious. The only thing I can find on ebay with this CPU in it is the
>  "eisse" 7in tablet with 256MB of RAM.

 search on taobao.com for jz4760 instead - you'll find dozens, if not
hundreds.  it really is a "PRC-only" CPU, basically.

>  With such openness, this CPU deserves to be a massive success. So why
>  are we all not voting with our feet? Why are there no products out there
>  to enable us to vote with our feet? If there is a project that has been
>  driving that point home for as long as I've been aware of it, it is this
>  one - and yet the current focus seems to be on an SoC with a closed-spec
>  GPU.
>
>  What am I missing?

 it can't do 1080p (and it was only 600mhz not 1ghz).  so it was just
too late.  if they had done the jz4760 even 1 year earlier, it would
have been "fantastic!" - 600mhz and 720p video in what... 2007, that
would have been, like... amazing, maaan!  with a $7 CPU, like... wow!

 ... but it couldn't do 1080p, so nobody in the western world would be
the slightest bit interested, regardless of price.

 by the time they got to 1080p (only a few months ago), they had for
some stupid reason added the vivante GC600.

 so it was just sheer bad luck that they missed out on the
"opportunity".  but.... you have to bear in mind, this is the company
that sold 25 milllllion MIPS-compatible CPUs (the 350mhz versions and
before) before MIPS themselves even noticed and went, "oi!  license,
sonny jim!   nowwww!" :)

 they also sell the realllly low-speed ones (150mhz) for use in MP3 players.

 with that in mind, you have to ask yourself, why in seven hells would
they want to bother with a market (rest of the world) that's only
going to be 1/10th the size of their internal market?

l.