Alan Stern wrote: > [...] and 11.17.5 where the text says > > When a bulk/control split transaction fails, it can leave the > associated TT transaction buffer in a busy (ready/x) state. > This buffer state will not allow the buffer to be reused for > other bulk/control split transactions. Therefore, as part of > endpoint halt processing for full-/low-speed endpoints > connected via a TT, the host software must use the > Clear_TT_Buffer request to the TT to ensure that the buffer is > not in the busy state. > > Admittedly, I don't see how a STALL handshake could be consistent with > a busy transaction buffer, so maybe the spec is wrong in this respect. It says that the purpose of the Clear_TT_Buffer is to clear the busy state; it seems to imply that the host driver can avoid sending that request if it can ensure in some other way that the buffer is not in the busy state. > Besides, Clear-TT-Buffer is supposed to be harmless if the buffer isn't > busy. It certainly shouldn't affect periodic transfers. I tried to reproduce this on my machine (2.6.32-rc6 +) by generating control requests that my audio device doesn't like, but it sounds as if my hub (some Genesys chip, 05e3:0605) doesn't break iso streaming. Regards, Clemens -- 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
