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

Luke Kenneth Casson Leighton lkcl at lkcl.net
Tue Mar 10 16:36:17 GMT 2015


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.

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).

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.

l.



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