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USB CPPI4.1 DMA RNDIS Mode Not working for Host Mode Rx Operation

rama krishna
Intellectual 695 points

Hello All,

              I am Working around the CPPI DMA RNDIS Mode in Host Controller instance(USB1). This instance is working well for transparent mode, but behaves unexpected behavior in RNDIS Mode.I have an EVMSK and AM335x EVM for Development Purposes.I wrote a simple CDC-ACM Host Driver for Communicating with the CDC Device.

This is the my test setup.

AM335x GP EVM USB0 Port is Connected to the USB 1 of EVM-SK.I take some dummy data in the Code and Send over USB 1 Interface of SK to the GP EVM. In The EVM that data is loop backed.

The USB1 Host Instance CPPI DMA for RNDIS is working for Transmission and for reception it is working like Transparent Mode.

The CDC Device(TX + RX) and CDC Host( Tx ) are woking Well for RNDIS Mode of DMA.We have a custom board with USB1 as a device, it is also working as expected.       

I have few queries regarding CPPI DMA.

1. Is that CPPI 4.1 DMA Working for RNDIS in Host Mode ?

The Data Packets are not re-assembled and comes as 512 byte transfer.I have check in the TX_Mode and RX_Mode registers of USB1 Instance ,that are Correctly Configured.

2.why this unexpected behavior of CPPI4.1 DMA for Host Instance?

3.Is there any Special Configuration required for Working in Host Mode?

4. Is there any errata for CPPI DMA for Host Controller Instance?

Is anybody faced similar kind of problem, please Address the issue?

Please guide me in the Correct direction.

Thanks & Regards

Rama Krishna