On Mon, 27 Jul 2009, Julie Zhu wrote: > And, for Xilinx's EHCI host controller with built-in TT, we do not have > any registers for special management of TT buffers. Since Xilinx's EHCI > host controller can be configured as HS only or HS/FS (which will have > TT), so we have a flag to show whether TT is in the hardware or not. > Software therefore can set the has_tt flag. In hardware, the host > controller is also aware of whether TT is built in. In the case when TT > is there, and if the directly connected device is FS (which enables TT), > then traffic is filtered by the TT. In the case if the HS control > transfer is a clear_tt_buffer, TT will clear its TT buffers. What HS control transfer? usbcore never sends control transfers or interrupt transfers to the root hub. Instead it calls ehci_hub_control() or ehci_hub_status_data(). > I wonder whether it is possible to add in a flag, such as > tt_support_clear_tt_buffer, which is default to be off. And if it is on, > then clear_tt_buffer can be sent to the root hub? You have to explain more clearly how the Xilinx controller expects to receive these messages. 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
