On 19.07.23 19:37, Alexandru Gagniuc wrote:
For Wake-on-LAN to work from S5 (shutdown), the USB link must be put in U3 state. If it is not, and the host "disappears", the chip will no longer respond to WoL triggers.
First, a question, does this also apply to S4?
To resolve this, add a notifier block and register it as a reboot notifier. When WoL is enabled, work through the usb_device struct to get to the suspend function. Calling this function puts the link in the correct state for WoL to function.
Second, do we really want this to be done for every driver with this issue or do we want a flag for core USB code to suspend devices when the system goes down? UAS at least does something similar.
Third, what happens if the device is already suspended when the notifier runs?
Regards Oliver