Linux/BEAGLEBK: Shared memory allocation with PRU using Remoteproc

David Lees

Part Number: BEAGLEBK

Tool/software: Linux

Hello,

In the above webpage, a method is shown where the uio_pruss driver is used to allocated shared DDR external memory to transfer larger amounts of data between the PRU and Beaglebone Black Linux userspace application. The PRU collects ADC data from MCP3008 chip and stores it in the shared DDR memory for access by the linux userspace application.

Can this be done - allocate and use shared DDR external memory between PRU and Linux userspace - using the new PRU Remoteproc and RPMsg drivers instead of uio_pruss? Is there an example available or webpage that explains how to do this?

I am using the TI RT Linux SDK 03.02.00.05 on Beaglebone Black.

Thanks,

David

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

The software team have been notified. They will respond here.

0 Jason Reeder over 8 years ago in reply to Biser Gatchev-XID

TI__Genius 10440 points

Please see these two wiki pages and let me know if this doesn't answer your question:

http://processors.wiki.ti.com/index.php/PRU-ICSS_Remoteproc_and_RPMsg

http://processors.wiki.ti.com/index.php/RPMsg_Quick_Start_Guide

Jason Reeder

0 David Lees over 8 years ago in reply to Jason Reeder

Prodigy 20 points

Hello Jason,

These two links do not answer my query and have no information about allocating and using DDR external memory to be shared between the PRU and BBB ARM Linux.

The uio_pruss method of allocating and using shared external DDR memory for PRU and BBB ARM Linux is quite popular and used in a number of DIY projects on the Internet.

If the PRU Remoteproc and RPMsg drivers do not have an equivalent method, how can the PRU stream data to the BBB Linux userspace and memory?

Regards,
David

0 Jason Reeder over 8 years ago in reply to David Lees

TI__Genius 10440 points

As the first wiki page shows, when requested, the Remoteproc driver running on the ARM core allocates circular buffers (known as vrings) in the DDR memory. These DDR buffers are then used by the RPMsg communication between the PRU and the ARM cores. PRU firmware examples of RPMsg communication between the PRU and ARM are provided in the pru-software-support-package: git.ti.com/.../PRU_RPMsg_Echo_Interrupt0. This is the current TI supported method of communication between the PRU and ARM.

If you would like to use the uio_pruss driver to directly memory map the PRU memories for user space then you will need to use the Debian distribution from the BeagleBoard community and further support will come from the BeagleBoard forums: http://beagleboard.org/discuss

Jason Reeder

0 Dmitry Sharihin over 8 years ago

Intellectual 420 points

You can reserve memory using CMEM (without RemoteProc at all), allocate some from ARM application and pass physical addressed pointer to PRU using RPMsg packet.
Anyway RPMsg is good for small packets (e.g. management), and direct memory allocation is better for large amounts of data.

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Linux/BEAGLEBK: Shared memory allocation with PRU using Remoteproc