On Mon, 27 Jul 2009, Julie Zhu wrote: > I see. However, for EHCI controller that has TT built in, sending > clear_tt_buffer there will be handled by our host controller and TT. Is > it possible to send this clear_tt_buffer to the root hub, as from > software to the hardware? It will not go to the bus because it will be > exchanged between the root hub and TT. If this breaks other TDI-type > designs, can we use a special flag? Sure, we will need to modify ehci_clear_tt_buffer() in ehci-q.c. The problem is to figure out a way to do it that will work with all the different types of controllers with built-in TTs. For instance, the datasheet for the Freescale MCIMX31 and MCIMX31L processors lists an ASYNCTTSTS register at offset 0x15c but leaves it out of the discussion of operational registers. There's no way to know if this register works or how to use it. The datasheet for the Freescale MPC8349EA processor lists the same register and explains how it works. The datasheet for Intel's IXP45X and IXP46X processors doesn't even list an ASYNCTTSTS register. Goodness knows how they manage their TT buffers. 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
