On Tue, 1 Dec 2015, Alan Cooper wrote: > I agree that for USB suspend modes, VBUS must be on, and our hardware > behaves that way for runtime suspend. The question is for system wide > suspend (S3/STR) can the system shut down the USB hardware entirely. Oh, okay, I misunderstood. > The ACPI spec and Linux Documents/power/states.txt seem to allow either > design. From states.txt under S3 mode: "In many cases, all peripheral buses > lose power when entering STR, so devices must be able to handle the > transition back to the On state". I'm not aware of any document stating whether USB buses should remain powered while an ACPI-based system is in S3. If it's not spelled out in the ACPI spec then it probably isn't mentioned anywhere. On the other hand, you should consider that if the bus isn't powered then remote wakeup will not work. This may be surprising to some users. Adapting wait_for_ss_port_enable() does seem like the best solution to the immediate problem. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
