On 2012年08月27日 03:18, Alan Stern wrote: > On Sun, 26 Aug 2012, Lan Tianyu wrote: > >> �� 2012/8/24 22:45, Alan Stern д��: >>> On Fri, 24 Aug 2012, Lan Tianyu wrote: >>> >>>>>> But if other places got hub descriptor, they can't get DeviceRemovable >>>>>> value since we only set DeviceRemovable in the hub_configure().(e.g lsusb). >>> >>> Note: This isn't true. You now set desc->u.hs.DeviceRemovable in >>> ehci_hub_descriptor(). >> Oh. Sorry. I maybe confuse you or make you misunderstand due to my broken >> descriptor. Do you agree set desc->u.hs.DeviceRemovable in ehci_hub_descriptor()? > > Yes. Ideally, those bits should be set even if the hub driver isn't > bound to the root hub device. > >> At the first time, the hub->maxchild is not set and port's device was not >> created so usb port has not been bound with acpi. usb port's ACPI information is >> not accessible at that time. The usb_get_hub_port_connect_type will return >> type_unkown. >> The value returned by first time of call get_hub_descriptor() will not be correct. > > Now I see the problem. The code you're adding to ehci-hub.c relies on > the hub driver knowing about the root hub's ports beforehand. So > you've got a circular dependency: > > ehci-hub.c depends on the hub driver knowing about the > root hub's ports; > > The hub driver learns the root-hub port connectivity > information by asking ehci-hub.c. > > The way to break this circle is to make ehci-hub.c use the ACPI > information directly rather than going through the hub driver's data > structures. But it's necessary to bind usb port with ACPI before using ACPI information. Otherwise there is no bright between usb port and it's ACPI information. Binding will be done during port's devices creating. Creating port's devices need port number of the root hub. So this must happen after first time of calling get_hub_descriptor. In short, there is a sequence of following steps. call get_hub_descriptor() || get port number, create port's device || bind usb ports with acpi and get ACPI information || set desc->u.hs.DeviceRemovable > > Alan Stern > -- Best regards Tianyu Lan -- 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
