USB Wakeup on i.MX 8M

[murreletinnovation]

Hi, I am referring to the i.MX Linux® Reference Manual, specifically Section 39.2.4. I am attempting to replicate the instructions provided on how to set the USB OTG as a wakeup when the system enters Suspend-to-RAM.

echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup

echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup

echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup

I do not see the these devices in the /sys/bus/platform/devices folder. Is there something that needs to be done on my end to make these devices available?

I'm specifically working off of a Google Coral Dev Board running the i.MX 8M SoC. I'm running Linux Mendel Eagle.

[murreletinnovation]

Hi,

The patches have already been applied by the Google dev team about a year ago. So the Mendel Kernel image that I was using must have had this workaround already implemented.

With that in mind, how would I go about enabling wakeup on a USB device? What commands do I need write to the CLI?

Thanks

[igorpadykov · Accepted solution]

it is necessary to run the following command before suspend to enable USB wakeup:

echo enabled > /sys/devices/platform/usb@38200000/38200000.dwc3/xhci-hcd.0.auto/power/wakeup

Best regards
igor

[murreletinnovation]

Thank you Igor! This did the trick.

[igorpadykov]

Hi murreletinnovation

unfortunately this may not work due to USB e11231 erratum

Mask Set Errata for Mask 2N14W

Best regards
igor

[murreletinnovation]

Hi Igor,

Thank you for the quick response. In the erratum, I see a potential workaround for this issue. 

"Requires RUN/STOP bit to be set to 1 during suspend mode."

Where exactly can I set the RUN/STOP bit?

Thanks!

[igorpadykov]

Hi murreletinnovation

additional patches were sent via mail.

Best regards
igor

[igorpadykov]

Hi murreletinnovation

additional patches were sent via mail.

Best regards
igor

[RayW8d]

Hi Igor,

I want to let an LTE USB device wake up the system. I have searched the kernel source tree (lf-5.10.y) but failed (maybe missed) to find the patch that implements the SW workaround for ERR11231.

Could you please send that patch to me as well? Thanks in advance.

BR

Ray

[murreletinnovation]

Hi Igor,

Thank you for the patches. I am trying to build the Mendel source tree with the patches. My environment wasn't originally set up to do so, so I am fixing that situation first. I will update when I am able to flash the device and verify if the USB Wakeup is functional.

Thank you