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? > isn't it possible the full speed device return NAK during transaction? Of course it is possible. > that mean once it react with NAK, the host will stop below transaction. The host stops the transaction temporarily. It will restart the transaction later. See section 4.9.1 in the EHCI spec. > How could we make sure device never react with NAK? There is no way to do that. > 2. I attach my mon log for your reference. > there is one thing I am curious > why below message 'E' mean in bulk/interrupt? > I have checked Document/usb/usbmon.txt but get nothing. E means the preceding submission failed. > d8c32600 190047566 E Bi:1:006:2 -19 0 > d8c32980 190062351 C Bi:1:006:2 -107 0 > d8c32980 190062363 S Bi:1:006:2 -115 1025 < > d8c32980 190072803 E Bi:1:006:2 -19 0 For example, this E means the submission on the line above was unsuccessful. The error code -19 is -ENODEV, which means the device has been disconnected. This is described in Documentation/usb/usbmon.txt: - Event Type. This type refers to the format of the event, not URB type. Available types are: S - submission, C - callback, E - submission error. 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
