2015-01-19 1:04 GMT+08:00 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Sun, 18 Jan 2015, Chechun Kuo wrote: > >> In check_port_resume_type, we will check port power status to determine whether the status should change to -ENODEV. >> If all ports power control of the hub are handled at once, the port power status may not represent the real case and cause resume fail. >> At this patch, we add hub_is_port_power_switchable as well as checking the port power. > > I don't understand the reason for this patch. > > Are you saying that the PORT POWER bit in the port status will be wrong > (that is, will be 0) if the hub doesn't support power switching? > According to section 11.24.2.7.1.6 of the USB-2 spec: > > This bit is implemented on all ports whether or not actual > port power switching devices are present. > > So why is this patch needed? Does it fix any real problems? this patch fixed the failure of runtime suspend happened on my host controller root hub. After reading what you point out above and ehci spec, I found it is our HW's issue for handling PP when PPC is zero. I am really sorry to make you confused ^^ Sincerely appreciate your kind help, -- 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
