On Sun, 1 Dec 2013, vichy wrote: > hi Alan: > > 2013/12/1 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > > On Fri, 29 Nov 2013, vichy wrote: > > > >> hi all: > >> My connection like below > >> ehci --> high speed hub -> full speed device > >> > >> I have some questions about period scheduling. > >> 1. when creating qh for full speed device, why we set EHCI_TUNE_RL_TT. > > > > Are you asking why EHCI_TUNE_RL_TT is equal to 0? I don't know -- it > > looks like a mistake. Do you find that changing it to 3 makes any > > difference? > Yes, when I change EHCI_TUNE_RL_TT as not 0. > The transaction can keep going. But if EHCI_TUNE_RL_TT is 0, the transfer doesn't work? > >> isn't it possible the full speed device return NAK during transaction? > > > > Of course it is possible. > If so, why we use EHCI_TUNE_RL_TT default as 0? Like I said above, I don't know -- it looks like a mistake. 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
