On 14.10.2024 11.50, Guan-Yu Lin wrote:
Sharing a USB controller with another entity via xhci-sideband driver creates power management complexities. To prevent the USB controller from being inadvertently deactivated while in use by the other entity, a usage-count based mechanism is implemented. This allows the system to manage power effectively, ensuring the controller remains available whenever needed.
I don't think all this is needed to prevent USB controller from being deactivated while sideband is in use. The modified audio class driver that uses sideband is still bound to a usb interface device, and all normal pm reference counting should work. To me it looks like this code is tricking pm framework into believing the usb device and host controller have successfully suspended during system suspend when they in reality are fully up and running. I'm not sure I fully understand the case this series is solving. Thanks Mathias
