SK-AM62: How user control USB_ID

Ryuuichi machida

Part Number: SK-AM62

Hello,

I would like you to confirm about below.

* According to TRM of AM62x, USBx_ID should be connected to GPIO.(Table 12-788. USB Control, Configuration, and Monitor Signal Pins) because this device do not have "USBx_ID" pin.
However, I'm not sure how assigned GPIO can connect USBxID internally.

I'm checking release note of SDK and document from resource explorer of linux academy for AM62, but there is no information about this.
I'm also searching "USB0_ID" or "USB1_ID" for source code of SDK, but there is any code that corresponding this search.
Do you have any idea to solve my above question ?

Best Regards,

over 2 years ago

0 Kallikuppa Sreenivasa over 2 years ago

TI__Guru**** 211360 points

Hello Ryuuichi machida,

Thank you for the query.

The below thread could be used as a starting point.

(+) AM625: USB DRD mode issue - Processors forum - Processors - TI E2E support forums

(+) AM623: USBn_ID vs physical pin association for USB dual-role (DRD) - Processors - INTERNAL forum - Processors - INTERNAL - TI E2E support forums

If you could please share some additional information on the use case, i could reassign to the expert.

Regards,

Sreenivasa

0 Ryuuichi machida over 2 years ago in reply to Kallikuppa Sreenivasa

Guru 13120 points

Hello,

Thank you for your reply.
However, I could not see second thread. It seems that this thread is internal E2E. I'm not TIer, so I can not access this site.
At first, I checked first thread.
However, this mentions only microAB and Type-C.
I would like to confirm case of Host-only or Device-only. (Type-A or Type-B)

I believe that user need to set USB-ID to fixed high or low(GND).
However, I'm not sure how this will be realized.
Could you please comment about above ?

Best Regards,

0 Kallikuppa Sreenivasa over 2 years ago in reply to Ryuuichi machida

TI__Guru**** 211360 points

Hello Ryuuichi machida,

Thank you for the inputs.

Please read the below that i copied from the thread and let me know if this helps.

If it is Host or Device mode fixed configuration, i guess you do not need the ID pin.

To use the USB-DRD functionality it is necessary to implement the “USBx-ID” signal.

According to current TRM it sounds like any available GPIO can be used for this purpose because there is no dedicated pin pointed to.

See snapshot of Table 12-788 from current TRM.

The question is if really meant “any GPIO” and how to tell the USB-IP which GPIO has been chosen as USB-ID pin.

The USB IP doesn't really care about this GPIO pin number. It is the software which receives the GPIO high/low interrupts then configures the USB IP to the corresponding mode.

If Linux is used, the GPIO pin information is specified in the kernel device tree. The detail is in the kernel device tree binding document.

Regards,

Sreenivasa

0 Kallikuppa Sreenivasa over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Guru**** 211360 points

Hello Ryuuichi machida,

Please refer below additional threads. In case you are looking to understand the implementation approach, these threads + above should help.

In case you are working on some implementation, let me know and i will assign to the USB expert.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1223596/am62a7-usb-subsystem-register/4622586?tisearch=e2e-sitesearch&keymatch=am623%252525252520host#4622586

https://e2e.ti.com/support/processors-group/processors---internal/f/processors---internal-forum/1113870/am623-usb-otg-support?tisearch=e2e-sitesearch&keymatch=am623%25252520host#

I copied the thread content below:

Based on other discussions (https://e2e.ti.com/support/processors-group/processors---internal/f/processors---internal-forum/1067047/am625x-usb-otg/3947942?tisearch=e2e-sitesearch&keymatch=am62x%25252525252520usb%25252525252520otg#3947942 ) it appears that OTG is not supported out of the box but it seems like it is possible to support it with the right SW that would configure device/host mode on the fly. Is this indeed the case? if it is - do we have any plans to support OTG use case in the Linux SDK?

Hi Michael,

As Paul explained in the e2e thread you referred, OTG and dual-role are two different things, OTG is never supported in Processor SDK for any TI processors. Are you referring to OTG (which supports role switch while the USB device is still attached) or dual-role (which role is decided upon the USB device is attached)?
Hi Bin,

I am referring to OTG. Paul explained that in the AM62x USB IP the role is decided based on register configuration so at the first glance it would appear that it should be is feasible to switch roles based on an event in the system without reattaching the cable. does it make sense or I am missing something?
Hi Michael,

I assume what you are looking for is to change the USB role without disconnect and reconnect, not the OTG protocol support such as HNP or SRP?

Technically it is possible to support USB role switching without disconnect and reconnect, but this is not supported in Linux kernel. The important factor is how to let both ends of the USB connection to tear down the enumeration then switch role at the same time. There is no single solution, so this scenario is not supported in Linux kernel.

Regards,

Sreenivasa