Hi, Alan, > -----Original Message----- > From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx] > Sent: Monday, July 27, 2009 9:16 AM > To: Julie Zhu > Cc: USB list > Subject: RE: Question on clear_tt_buffer for not TDI but with built-in TT > > On Mon, 27 Jul 2009, Julie Zhu wrote: > > > > > 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. > > > > > > > In our case, we do provide a way to send the notification, just as the > > way the USB spec says, through a control message of CLEAR_TT_BUFFER. How > > can we send this message out, even we have built-in TT? Do we need a > > special flag? > > Your question doesn't make any sense. The kernel doesn't send _any_ > control messages to root hubs, because root hubs don't have an upstream > USB port through which to receive them. > > So what do you mean by "send this message out"? Where are you going to > send it out _to_, considering that the intended destination (the host > controller's root hub) is actually part of the computer? > 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? > Alan Stern Thanks, Julie. This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately. -- 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
