> +++ Steve Wiseman [2011-05-24 08:04 +0100]:
>> On Tue 24/05/11 07:16 , "P.J.G. Long"<pjgl2@cam.ac.uk> wrote:
>>
>>> The low end console/display market seems to be moving HDMI, they are
>>> becoming more common on netbooks. I can see for a number of low end
>>> users using it as the cheap route to a display. See the Raspberry! Looking
>>> at the feedback I think there may be a market for the Balloon as the up
>>> market interfacable unit
>> This still isn't a use case.
>> Is it simply that, without a monitor connection of some sort, it's not a 'proper computer?
> To some degree, yes. It's certainly not a convenient computer, although ssh and
> remote X goes a long way to solving this in a different way.
>
Well, we have hardware graphics acceleration available. Without monitor
output of some sort it is limited to being only an inconvenient embedded
development system. I guess that support will come from a variety of
customers including those that might otherwise look at beagle. If we don't
match their convienience of use we loose critical mass of developers. If I
wanted a headless system I might look at a Dreamplug and uses it eSata port
for storage instead. Not being headless is a distinguishing feature for
Balloon4. Why add a camera(s) and not be able to convenently view the
output in real time.
If I want to try Ubuntu (Unity flavour) or Wayland or OpenCV or anything
else that uses opengl, not having monitor output is a big turn-off. Is
Android predicated on 3D acceleration now? I doubt HTML5 codecs / flash
plugins perform well over vnc.
I am not making a case for lots of board real estate/power being devoted to
HDMI, just to make sure we don't option out connectivity that some would
regard as expected. The form it takes probably doesn't matter and off-board
is fine if HDMI is needed by a product.
I can easily imagine a future TCL product glued to a television with
bespoke (hence Balloon4 derivative) wireless input coming from the patient.
>> During development, there will always be a desktop / laptop machine
>> being used for compilation, and it'll have a decent display, on which
>> X works well, also serial terminals, xterms, ssh, whatever. Who really
>> wants yet another monitor on their precious desk space, running scaled
>> HDMI? That implies another keyboard, too.
> Not if you do native development, which is what Debian and Ubuntu push
> you towards and it's more and more practical as the arm hardware gets
> better. Balloon4 will be at least as fast as a PC from a few years
> back (pentium III?) and native dev there was no problem.
>
>> In short: If you want to drive an HDMI TV, a PC is probably cheaper.
>> You've obviously got mains available, so you don't care about power.
> Wrong. I always care about power. And so should everyone.
>
The power issues should be resolved at the Balloon4 derived product level
(eg Challenger) and not be a design limitation surely.
>> You've obviously got space available, so stick a Revo on the back of
>> your TV if you want to pretend to be 'integrated'.
>> If I exposed the DSS as 28 precious GPIOs on a connector, (or 24
>> GPIOs and SPI3), and let people add an HDMI chip& connector, would we
>> sell any of those, ever?
>> Would we sell any IO boards that sat there instead and protected
>> those (1.8V) GPIO pins, and exposed them at student-friendly levels&
>> connectors?
> This is the real question. Is it worth the pins? I don't have an
> answer to that. So long as we are happy with the answer 'go buy a
> beagle if you wanted to plug it into a TV' then we don't need it.
>
> Ethernet and DVI/VGA/HDMI are incredibly convenient for development.
> If we only provide those on a dev-board then that's OK, but lets try
> not to have a 3-yr gap between board and dev-board this time in that
> case. Ethernet is more important than video.
>
>> If DVI/HDMI over USB works as well as it seems, then why would we
>> want to sit there squandering precious memory bandwidth spewing pixels
>> down a wire? Plug in a display when you want to do a demo on a
>> projector or something, but the other 99% of the time, run headless.
DisplayLink hardware, while remarkably useable, does not survive
suspend/resume (at the moment in 2.6.38.2) due to taking down USB and not
re-initialising the device correctly after it is powered up. It is not a
full solution.
>> (The memory bandwidth issue isn't specious. 720p60 is 240MBytes a
>> second, of unstoppable high priority data. Not sure if it pollutes the
>> cache or not.)
> If it does indeed work over USB then that's OK, (do we have 240MB/s
> over USB?) And do we have enough USB sockets for ethernet, video,
> serial, keyboard,<something else>? The need for a hub to do almost
> anything on B3 was tiresome in practice.
>
>> (I'm trying to think of a time when you'd want both Balloon's FPGA
>> resource, and a genuine framebuffered, pixel-painting display on a TV,
>> and I can't. Something that needed the 3D graphics engine of the OMAP,
>> on a projector, maybe?)
Stereo cameras + FPGA CUED wizardry1 + beagle inspired TMS320 wizardry2?
> I amdit I don;t understand the difference between LCD and
> DVI/VGA/HDMI. Don't they all amount to "a genuine framebuffered,
> pixel-painting display"?
>
> Any display will do, widely available ones with standard connections
> are just easy to dev with.
>
Agreed.
> Wookey
NickB
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