AM623: Checking device connection status on AM62 platform

Sakshi Koundal

Part Number: AM623
Other Parts Discussed in Thread: SK-AM62B

Hi team,

I'm currently working on the AM62 and I'm seeking assistance regarding USB device connection status monitoring. I've been exploring the driver, but I haven't come across a clear indication of a sysfs entry dedicated to providing device connection status.

I wanted to know, if there's a direct sysfs entry available that allows us to determine whether usb is connected or disconnected.

Thanks in advance.

6 months ago

0 Bin Liu 6 months ago

TI__Guru*** 140946 points

Hi Sakshi,

Which AM623 USB port do you use? Is the port in USB host mode or device mode?

0 Sakshi Koundal 6 months ago

Prodigy 40 points

Hi,

I'm using it in device mode.

0 Bin Liu 6 months ago in reply to Sakshi Koundal

TI__Guru*** 140946 points

Hi Sakshi,

For USB0 port, you can read the following sysfs entry:

/sys/devices/platform/bus@f0000/f900000.dwc3-usb/31000000.usb/udc/31000000.usb/state

0 Sakshi Koundal 6 months ago in reply to Bin Liu

Prodigy 40 points

I tried reading the state entry already, it shows "configured" when usb is connected to am623, and "not attached" when usb is disconnected from am623, but it still shows "configured" when one end is connected to am623 and other end is disconnected from host.

So, even in that case, it should be showing "not attached" right? like we have the link-state entry in debugfs.

0 Bin Liu 6 months ago in reply to Sakshi Koundal

TI__Guru*** 140946 points

Sakshi Koundal said:
but it still shows "configured" when one end is connected to am623 and other end is disconnected from host.

On SK-AM62B USB0 which uses type-C, it shows "not attached" when the USB cable is in type-C port but the other end is disconnected from host.

Maybe use debugfs entry:

/sys/kernel/debug/usb/31000000.usb/link_state

0 Sakshi Koundal 6 months ago in reply to Bin Liu

Prodigy 40 points

yes, the link-state provide correct information but since, debufs will be removed in production, we can't use that for our requirement. So, I was looking for some sysfs entry, but the state entry does not give reliable output in our case.

Does dwc3 diver provides any other entry we can use for the same? or some changes we can add to driver to get that.

0 Bin Liu 6 months ago in reply to Sakshi Koundal

TI__Guru*** 140946 points

Can you see if you can use the current_speed entry? It doesn't really tell the "link" state, rather enumerated or not.

/sys/devices/platform/bus@f0000/f900000.dwc3-usb/31000000.usb/udc/31000000.usb/current_speed

If this doesn't help either, you might want to modify the dcw3 driver to add link_state to dwc3 sysfs driver by copying from its debugfs driver.

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AM623: Checking device connection status on AM62 platform