[USRP-users] Problems using dsplink on E100

Thomas Tsou ttsou at vt.edu
Sun Feb 26 22:16:12 EST 2012

On Wed, Feb 22, 2012 at 3:45 AM, Andre Puschmann
<andre.puschmann at tu-ilmenau.de> wrote:
> @Al Thanks for explaining the difference between dsplink and syslink.
> I believe, remote_proc (or RPMsg) successes even syslink but is only
> available for OMAP4 and beyond if I am not mistaken.

Indeed. But still, even if there was support for omap3 with RPMsg
(SysLink 3.0), one has to wonder what benefits that approach would
provide to the E100.

SysLink and beyond really evolved to handle the asymmetric
multiprocessor environment with 5 or more different cores. That's a
problem omap3 doesn't have when a simple master/slave approach is
adequate. I can see the benefit (or detriment) of being bleeding edge
and on the Ice Cream Sandwich upgrade track, but that's about it.

The other factor of future portability is that DSP access (independent
of video or imaging units) remains uncertain. Look up DSP Subsystem in
the omap4430 TRM and you'll find that "This information is not
available in the public domain." The omap4 includes a reduced
functionality c64x, 'Tesla', but you won't be able to access it
without an NDA, which is incredibly unfortunate.

In short, I find little motivation to go beyond DSPLink on the E100 at
this time (I can deal with the fact that DSPLink code is just plain
ugly). If you're concerned about future portability, refer to the
SysLink migration guide and be mindful of the differences. There are
SysLink counterparts for many, but not all, DSPLink interfaces.


> In general I would really like to see something that nicely combines
> both worlds on the E100 (and beyond it). Integrating an interface for
> adding/removing DSP blocks into UHD would also make sense, since radio
> parameter configuration would be done using UHD anyway. But not sure
> though how something like this could look like.

What role do you see for the c64x inside of UHD?

I view the DSP as more of an application side processor. Even with an
fpga->c64x interface (no small feat), I feel that UHD interface should
end at the transport. The subsequent c64x signal processing code
should be independent of how the samples got there.


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