On 2012年08月27日 14:57, Lan Tianyu wrote: > 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 Excuse me, a typo "bright" => "bridge" > 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
