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AM3352: issues with the MUSB driver

Errol Leon6
Expert 5850 points
Part Number: AM3352

Hello team,

My customer is having issues with the MUSB driver of the AM335x Linux SDK, kernel version 4.19.59. Apparently, the driver is unable to reserve DMA channels for its operation. They have had to build their kernel disabling DMA, using program I/O instead. This leads to a significant increase in the CPU utilization.  Is there a way around this to be able to utilize the DMA to optimize CPU utilization?

Thanks in advance for your support!

Errol

  • 0
    TI__Guru**** 167681 points

    Hi Errol,

    Please explain what the issue is with MUSB DMA, so that we can figure out how to resolve it.

  • 0
    TI__Guru**** 167681 points

    Hi Errol,

    Thanks for sending over the details of the issue report offline. The issue seems to be mis-configuration in device tree.

    The am335x-evm.dts has the following entry to enable the CPPI41 DMA, but it is missing in the customer's board device tree file. Please ask the customer to add this entry in their board device tree file and let me know if it solve the problem.

    464 &cppi41dma  {                                                                   
465         status = "okay";                                                        
466 };