If trying to pull data from the PRU, into userspace Linux. You may wish to
consider mmap()ing the 8k PRU data ram, or he 12k shared PRU ram. Then, you
just toggle a bit somewhere in that ram, to let  the PRU tell the userspace
side it's ok to copy. I've done this from userspace to userspace as a way
of locking a shared memory file, and it is very fast.

If speed is paramount, You may wish to involve both PRU's, broadside the
data from one to the other, and then have the second PRU communicate with
userspace. I'd have to give this some more thought after writing
experimental code to make sure of a couple things. But I'm fairly sure this
is a good way to approach this sort of problem.

As for remoteproc . . . not idea what remoteproc is capable of. But
uio_pruss can do this fairly easily.

On Sun, Jun 26, 2016 at 10:57 AM, Greg <[email protected]> wrote:

> I'm working on a similar problem, but it's the opposite direction.  I'm
>> trying to pull data from the PRU, into the ARM.
>>
>
> What are you using for a data structure in the PRU to hold the data?
> Have you looked at the user-space C program in Lab 5 called
> rpmsg_pru_user_space_echo.c ?
> It's perhaps not the best example to illustrate what to do, but note the
> "open/read/write/close" functions which are a fundamental POSIX way to
> read/write data.
>
> I'm thinking that if you have an array declared to hold 1152 bytes in the
> PRU, you could do three transmissions from user space and fill your array
> in the PRU.
>
> I'm very new to this, so what I am suggesting may be very inefficient, but
> I think fundamentally it should work.
>
> Greg
>
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