Yummy new CPU/GPU combo

David Samblas Martinez dsamblas at yahoo.es
Fri Jun 6 09:08:41 CEST 2008

There is any posibility to change the screen resolution without reboot?
If we can do so we can dinamically change it to got the best of two worlds, a high resolution for almost statical screens to webbrowsing, doc editing, picture viewing, an a low resolution to mame, video playback(?), and anything else doesn't fit on high res. It can be done?


--- El vie, 6/6/08, Carsten Haitzler <raster at openmoko.org> escribió:

> De: Carsten Haitzler <raster at openmoko.org>
> Asunto: Re: Yummy new CPU/GPU combo
> Para: "List for Openmoko community discussion" <community at lists.openmoko.org>
> CC: "Tom Cooksey" <thomas.cooksey at trolltech.com>
> Fecha: viernes, 6 junio, 2008 4:36
> On Thu, 5 Jun 2008 12:56:00 +0200 Tom Cooksey
> <thomas.cooksey at trolltech.com>
> babbled:
> > Well... yeah, that's kindof the reason for the
> initial post! I must have
> > misunderstood previous posts as I was convinced the
> glamo was itself attached
> > to the CPU's SDIO interface. You can understand
> where I was coming from now!
> :)
> > Right. Shame the cpu doesn't have more cache so it
> has a better change of
> > getting on with something else while the DMA occurs.
> > 
> > Thanks for clearing things up. It's good to hear
> that the problem isn't
> > because of any particularly bad decision on
> OpenMoko's part. Renews my faith
> > a little. :-)
> glamo is a fairly old graphics cpu and design. frankly it
> was designed for qvga
> - at best. it CAN do vga, but that is beyond its intended
> use. we have pushed
> it much farther than smedia intended it to be - even smedia
> is amazed at the
> bus speeds we get to the glamo - they have never seen it so
> fast.
> glamo turned up primarily for 2 reasons.
> 1. we added wifi - and we just didn't have any other
> (good) interfaces (we can
> sit and discuss spi all u like right now - but lets hold
> that thought). so we
> needed to use up our sdio port for... wifi - but where will
> we stick the actual
> sd card? glamo came with its own sd interface - bonus, so
> we get that back
> again.
> 2. refresh. we run a vga screen. 640x480x70x2 - 41mb/sec
> ... JUST to refresh
> the screen. we lost 41mb/sec of memory bandwidth just to
> keep the screen
> displaying on the gta01. vga was by far pushing what the
> soc can do. literally
> that is a huge amount of the bandwidth we had left (as its
> reads only and we
> clock @ 100mhz for the bus clock on the gta02, it's be
> about 20% of memory
> bandwidth gone). the glamo removes that drain and gives u
> back bandwidth... but
> at another cost - the glamo's own bus and the extra
> work to write acceleration
> to keep as much on the glamo as possible. we definitely
> don't do everything we
> can on the glamo - but there is only so much time and
> development effort to go
> around. as such we only really knew what the glamo was like
> once we had it
> going reasonably, and by then - it's too late. glamo is
> in. it's not going away
> as there just is no alternative.
> so solutions could be: ditch vga, go to qvga, thus dropping
> mem bandwidth loss
> to 10mb/sec (1/4 of what it was), and now have to drive
> only 1/2 the pixels in
> software. end result would be much lower dpi, but much
> smoother and nicer
> performance. but then go all the cries of "i must have
> vga!!!" (though i wonder
> just how many people have good enough eyesight to really
> tell the difference).
> if we want to live in the realms of such high resolution,
> imho, we need to look
> very carefully at a high-end soc with good on-board
> graphics acceleration, but
> that would have put the freerunner on hold as a product for
> a looong time. so
> you would all still be waiting and waiting. no one would be
> talking of
> production runs right now! :)
> -- 
> Carsten Haitzler (The Rasterman)
> <raster at openmoko.org>
> _______________________________________________
> Openmoko community mailing list
> community at lists.openmoko.org
> http://lists.openmoko.org/mailman/listinfo/community

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