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Linux/PROCESSOR-SDK-AM335X: USB questions

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Part Number:PROCESSOR-SDK-AM335X

Tool/software: Linux

Hi

I have few queries on the USB subsystem and wanted a little clarification. My lInux kernel is 4.9.31.

1. USB DMA (USB_TI_CPPI_DMA) is enabled in my kernel configuration.. so my question is what size FIFO buffer is used? Is buffer size adequate for HS interface data transfer needs?

2. What will be the minimum time for detection of a USB flash drive (default musb controller mode is set to otg in the dtb file)

3. What is the maximum time required to switch between USB host and device modes? For instance, if I need to plug in a USB cable (for RNDIS connection) and quickly plug it out and plug in a USB flash drive then.. how much time do I need to give between for the mode switch to happen (from device to host mode or vice-versa)

4. Considering it is possible to change USB speed (full speed/high speed) using dtb.. if i use a dtb overlay file and then configure this.... i,e initially usb is configured for high speed and during the course of my test, I change it to full speed using dtb overlay. will this work or do I need to reset the USB subsystem (using a command) or reload drivers?

5. If USB device doesn't get detected and I need some info.. will there be any information that I can get from Linux kernel (other than the prints) via sysfs/procfs etc.

6. Finally, the ID pin status is detected in hardware and the information that a flash device is plugged in/a usb cable (RNDIS) is given to the USB driver via an interrupt I suppose. Please confirm.

Regards,

Fariya 


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