> On Feb 20, 2016, at 9:39 PM, William Hermans <[email protected]> wrote:
>
> William,
>
> I must be missing something, because I see remoteproc as a
> communication and management mechanism for code on CPUs other than the
> main processor. The actual code that you are running on those
> subsidiary processors does not depend on the mechanism you use for
> talking to it (other than the parts that do the talking, of course).
>
> In particular, running ADC, I2C or GPIO should be the same, regardless
> whether you use remoteproc or not---what changes is how you tell this
> code what to do.
>
> Does it make sense to you?
>
> What it is suppose to do hs always made sense to me. How exactlyit is done,
> is another story.
>
> with uio_prussdrv, you have a driver module, which sets various things up,
> loads the PRU binary, and then enables / runs the PRU(s). On the PRU side,
> the code runs, communicates with various peripherals as needed( usually one,
> if any ), and then the PRU code performs it's function as specified in
> assembly. Sometimes, dumping data into ddr3( as per the example ), and
> sometimes not.
>
> Anyway, the above is a fairly rough description, but how each aspect
> communicates with the other is abundantly clear in code. Some have even
> attempted to describe what happens, but if you ask me inadequately. No matter
> though the code is pretty clear.
>
> With remoteproc, the Documentation/*txt documentation is very minimal, and
> does not describe the process in which it works very well. However, the code
> is fairly clear as to how the ARM, and PRU sides communicate with one
> another( rpmsg ). However, what is not clear, is how the PRU code actually
> manipulates the physics on system hardware. Additionally, to confuse matters
> even more, the assembler has changed to a compiler( C - clpru ), and there is
> something like "map" files for hardware configuration that do not seem to be
> very well documented. Just some examples, that are not very clear as to how,
> or why these are even needed.
What do you mean by “how the PRU code actually manipulates the physics on
system hardware?
This is standard PRU code that toggles PRU dedicated IO, sets/clears register
values of peripherals, in exactly the same way as the code that you run via
prussdrv which is just doing the same, but via UIO. I think you are just
pulling my leg here. This is trivial stuff. What is complicated? I’m scratching
my head and totally confused ;-)
Regards,
John
>
> So here I am, attempting to learn a few things new to me. Documentation is
> very poor, TI refuses to answer any questions in relation to PRUs on their
> e2e forums(" go to beagleboard.org <http://beagleboard.org/> google groups .
> . ." ). I spend several days learning about everything PRU related, and
> immediately pick up the concept of uio_prussdrv. Still having a hard time
> with the TI C compiler on the PRU side of things, largely due to these
> mysterious configuration files. But no matter, the TI Assembler is fairly
> straight forward, the PRU instruction set is a minimal Cortex M3 set, and
> easy.
>
> Anyway, for context of my competence level. Not long ago I wrote a set of
> processes / applications to read from the CANBUS in realtime, decode the
> CANBUS data, and shuffle this decoded data out over a websocket. This
> required me learning several aspect of Linux systems programming from
> scratch. Including POSIX shared memory files, socketCAN, and process spawning
> / management. All from scratch, since this was my first major Linux
> application. All of this including reverse engineering parts of the high
> level CANBUS protocol took me around a month. The point here is, I have no
> problem picking up / understanding technologies, and / or API's, libraries,
> and such that I've previously have had no experience with. *So long* as there
> is at least a little decent documentation on the subject, or I can talk to
> someone who does understand things that may be confusing to me.
>
> Additionally, I'm not saying exactly that remoteproc can't be made to work,
> because obviously it can. What I am saying is that since the concept is so
> poorly documented, is still in experimental phase, and now I learn that it is
> slower than traditional prussdrv drivers / methods. That it's just not worth
> my time to even attempt to get working.
>
> That and I *have* spent some time ( roughly a week ), *just because* I'm the
> type that does not mind experimenting with new technology in software. But
> only new technology that is not too argumentative. As my time is far too
> valuable to me than to screw around with technology that honestly makes very
> little sense to me.
>
> Also for what it is worth. remoteproc / rpmsg in my own mind is far more
> useful in cases where a processor may have multiple application / general
> purpose cores. In that one core can be made to run Linux, while the others
> can be made to run bare metal - Simultaneously. Less useful on the case of
> the PRUs since we already have a software layer that is well documented,
> works very well, and quite honestly far superior to remoteproc / rpmsg in
> this case. If nothing else. Speed.
>
>
> On Sat, Feb 20, 2016 at 9:45 PM, Przemek Klosowski
> <[email protected] <mailto:[email protected]>> wrote:
> On Sat, Feb 20, 2016 at 2:45 PM, William Hermans <[email protected]
> <mailto:[email protected]>> wrote:
> > Is it really so much to ask for example code to demonstrate how to interact
> > with the on die hardware ? Without having to download 1GB of pretty much
> > useless library . . .
>
> William,
>
> I must be missing something, because I see remoteproc as a
> communication and management mechanism for code on CPUs other than the
> main processor. The actual code that you are running on those
> subsidiary processors does not depend on the mechanism you use for
> talking to it (other than the parts that do the talking, of course).
>
> In particular, running ADC, I2C or GPIO should be the same, regardless
> whether you use remoteproc or not---what changes is how you tell this
> code what to do.
>
> Does it make sense to you?
>
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> <http://beagleboard.org/discuss>
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>
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