Yummy new CPU/GPU combo
Carsten Haitzler (The Rasterman)
raster at openmoko.org
Fri Jun 6 17:18:04 CEST 2008
On Fri, 6 Jun 2008 07:08:41 +0000 (GMT) David Samblas Martinez
<dsamblas at yahoo.es> babbled:
> 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?
you can change screen res any time. assuming the drivers don't get it wrong, it
will work just fine even runtime while x11 is up (xrandr will manage it). your
transition from qvga to vga won't be smooth - you'll see flicker and things
move/redraw/adjust, and right now xglamo seems to be doing a wonderful job of
not switching properly, but as such it is perfectly possible to do it runtime
without even finishing your x session.
note - qvga really does look blocky on the 2.8" vga....
> --- 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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Carsten Haitzler (The Rasterman) <raster at openmoko.org>
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