OMAP-L138: CPPI DMA with MUSB

Part Number:OMAP-L138

Hello everyone,

I am using OMAPL138EVM and running Ethernet on MUSB with both I and D caches enabled. When I ping this target from other machine, I get replies but there are occasional timeouts. Then it completely stops working after some time. In one of linux commits, I saw the following comment:

"For the am3517, am180x, and am335x devices the CPPI 4.1 DMA should NOT be used for the MUSB controller. Using this DMA can cause the controller to lockup."

I did a few experiments and following are my observations:

1. With CPPI DMA disabled, no issues appear at all.
2. With any of the (instruction or data) cache disabled, no issues at all again.

I want to ask what does this lockup mean? Is it something specific to linux or a hardware bug (Remember I am not using linux)? Is my case also having a potential lockup?

Waiting for your reply,

Muhammad Umair Khan