AM3352: Set USB to full speed mode only

Tony Tang

Part Number: AM3352

On customer's board, there is signal Integrity issue on USB, so would like to set to full speed other than high speed.

This post told how to set to full speed:

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1165072/processor-sdk-am335x-am335x-usb-communication-issue/4386290

How to set USB to full speed in V3.12.10 Kernel SDK? which should be SDK7.0: https://software-dl.ti.com/sitara_linux/esd/AM335xSDK/07_00_00_00/index_FDS.html

over 2 years ago

0 Bin Liu over 2 years ago

TI__Guru**** 168761 points

Hi Tony,

Your post is not properly formatted, so I am not sure I understand it. Does your customer use kernel v3.12.10? If not, what is the kernel version used? Please note v3.12 is very old an no longer supported, I am unable to review the older kernel to provide a patch to set MUSB in full-speed mode.

0 Tony Tang over 2 years ago in reply to Bin Liu

TI__Mastermind 29172 points

Bin Liu said:
Does your customer use kernel v3.12.10

Yes, from my record, it is SDK7.0.

Bin Liu said:
Please note v3.12 is very old an no longer supported, I am unable to review the older kernel to provide a patch to set MUSB in full-speed mode.

understood, but this is a key Sitara customer, if tell which register to configure also help.

0 Bin Liu over 2 years ago in reply to Tony Tang

TI__Guru**** 168761 points

Tony,

Please see the code in musb_start() in the current kernel v5.10:

https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/drivers/usb/musb/musb_core.c?h=ti-linux-5.10.y#n1206

this function is very much similar to v3.12.

clearing MUSB_POWER_HSENAB bit in MUSB_POWER register will force MUSB in full-speed mode.

If you also search on the e2e forums, I should have provided the patch for v3.12 a few times many years ago.

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AM3352: Set USB to full speed mode only