[Arm-netbook] fsf-endorseable ingenic jz4775 cpu card can go ahead

Paul Boddie paul at boddie.org.uk
Tue Mar 10 17:15:48 GMT 2015

On Tuesday 10. March 2015 17.36.17 Luke Kenneth Casson Leighton wrote:
> good news: after being very patient and persistent, my contact at
> ingenic put me in touch with a support engineer who confirmed that the
> limitation on the jz4775's reported maximum resolution (1280x720) is
> for the *video decoder* not the actual LCD output capabilities.  the
> actual LCD output may go as high as something like 1700x1700 (not at
> 60fps obviously) but that things like 1280x800 @ 60hz (the crucial
> limit of the eoma68 spec) are fine, as is even 1366x768 at 60hz.

So it's the VPU that only supports 720p, rather than an actual video output 
limit of 720 lines. I suppose that's what they're trying to say on the 
following page:


Some day, even smartwatches will need more than 720p video playback for those 
who are bothered by that kind of thing. ;-)

> however he did kindly point out that if 720p video decoding [for which
> the full source is apparently available, which is also great] is
> attempted to be displayed on a 1366x768 LCD (or greater), there is a
> bandwidth memory limitation between the video decoder and the lcd
> buffer which would prooobably end up stalling slightly so that 30fps
> would be hard to achieve, at full-screen.
> honestly, i really don't see this as being a huge show-stopper enough
> to warrant exclusion of a low-cost SoC that could be the first
> FSF-Endorseable candidate to run GNU/Linux OSes with a decent amount
> of RAM (2Gbytes).

I'd certainly be interested, and I would imagine that it would be a good 
alternative to the various non-open-hardware boards that have been emerging 
recently for the MIPS platform, as well as a solid alternative to certain 
popular ARM-based single-board computers.

> as i've had the first revision PCB done nearly 4 months ago, that just
> leaves financing of the first revision jz4775 CPU Card to arrange.  i
> have one potential sponsor: if anyone else would like to help out that
> would be great.  we're likely looking at around $USD 1,500 for 5 PCBs.

I don't think I'd be aiming to be a sponsor as such, not being an organisation 
that would get involved because they see the commercial value in what you're 
doing, but I'd certainly be interested in seeing this card come to fruition, 
as indeed I am about the microdesktop and other things getting made.

Actually, with regard to the crowd-funding effort, was it going to include the 
IC1T board as well as the A20 board, and would the jz4775 board also join the 
crowd-funding line-up if successfully produced as a first revision?


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