AM3352: Not getting '/proc/driver/musb_hdrc.1' even with TISDK v9.01.1

Harsh Patel35

Part Number: AM3352

Tool/software:

Hi TI Team,

I want to enable/disable AM3352 USB0 port power from sysfs which doesn't have external USB hub on board.

In USB1 power control with DRVVBUS - Processors forum - Processors - TI E2E support forums, TI recommended "echo F > /proc/driver/musb_hdrc.1" to control USBx_DRVVBUS.
With SDK v9.01.1, I cannot see this path so can you please recommend a way to enable this feature or other option to control USBx_DRVVBUS from sysfs?

Thanks.

4 months ago

0 Bin Liu 4 months ago

TI__Guru**** 168181 points

Hi Harsh,

Can you please explain why do you need to control the USB port power? Software directly control the DRVVBUS pin is not officially supported in Linux.

0 Harsh Patel35 4 months ago in reply to Bin Liu

Intellectual 330 points

Hi Bin Liu,

Thanks for quick response.

An external Modem connected to AM3352 USB port thus it is getting power from USB port and want to runtime toggle modem power.

Regarding your statement, "Software directly control the DRVVBUS pin is not officially supported in Linux":
- Is there any unofficial way?

Well, expecting sysfs interface provided by usb driver so the user can on/off usb port power. There are many options under "/sys/bus/usb/devices/usb1/power/" but none of helped.

+1 Bin Liu 4 months ago in reply to Harsh Patel35

TI__Guru**** 168181 points

Hi Harsh,

My AM335x board is not up and running at this time for me to check the exact sysfs entry, and I am about to leave the office now, but here is the guideline.

Assuming you have kernel devicetree set usb0 dr_mode to "host", please look for "softconnect" entry under /sys/kernel/debug/usb/ directory, echo '0' to this entry for usb0 should pull-down USB0_DRVVBUS pin, and echo '1' to it should pull-up the pin.

0 Harsh Patel35 4 months ago in reply to Bin Liu

Intellectual 330 points

Hi Bin Liu,

Wish you have a good evening...!!

As usual, you input always helps. Using this way, able to control the USB port power so it will help.
Just want to double check do you see any side effects (in terms of AM3352) of using this indirect USB port power control method?

Thanks.

0 Bin Liu 4 months ago in reply to Harsh Patel35

TI__Guru**** 168181 points

Thanks Harsh.

This debugfs entry was implemented about 10 years ago for the exact same request as yours and I didn’t receive any complaint. So if you run through out test and don’t find any issue, it should be safe to use it.