19 Jul
2023
19 Jul
'23
6:36 p.m.
On Wed, Jul 19, 2023 at 05:37:56PM +0000, 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.
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.
How do you know that the link will _remain_ in the correct state?
That is, how do you know that the shutdown processing for the USB host controller won't disable the link entirely, thereby preventing WoL from working?
Alan Stern