hi 2013/12/2 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > 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? No. the transaction will stop since device return Nak. I copy the usb traffic log for your reference. usually device will not return NAK in setup token. but in my case, it did. Thanks for your kind help,
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