On Fri, 24 Jul 2009, Julie Zhu wrote: > Hello, > > I have a question about the interface for clear_tt_buffer that has been > added into 2.6.31-rc3. We are working with an EHCI host controller that > has a transaction translator built-in. Therefore, it is naturally TDI > (by ehci_is_TDI() check for has_tt). In the handling of clear_tt_buffer, > if it is TDI, then clear_tt_buffer control message is not sent out. > However, we do not have the way that is commented in ehci-q.c: > > /* REVISIT ARC-derived cores don't clear the root > * hub TT buffer in this way... > */ > > We actually need the clear_tt_buffer control message sent to the > built-in transaction translator. What should we do? This is an important issue. It turns out that some TDI-type designs require the built-in TT to be notified when the buffer has to be cleared and some don't, or at least, they don't provide any way to send the notification -- I don't understand why not. I don't know what the best approach will be. > I believe the clear_tt_buffer control message is to notify the > transaction translator about software-side cancellation/failure? I know > we can handle hardware-side failures just fine without the need of > clear_tt_buffer control message. Yes, that is correct. 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
