> -----Original Message----- > From: Elric Fu [mailto:elricfu1@xxxxxxxxx] > Sent: Thursday, March 29, 2012 5:13 PM > To: Sarah Sharp > Cc: Xu, Andiry; Elric Fu; linux-usb@xxxxxxxxxxxxxxx > Subject: [RFT v2] xHCI: cancel command queued in the command ring > > Software have to abort command ring and cancel command > when a command is failed or hang. Otherwise, the command > ring will hang up and can't handle the others. An example > of a command that may hang is the Address Device Command, > because waiting for a SET_ADDRESS request to be acknowledged > by a USB device is outside of the xHC's ability to control. > > According to xHCI spec section 4.6.1.1 and section 4.6.1.2, > after aborting a command on the command ring, xHC will > generate a command completion event with its completion code > set to Command Ring Stopped at least. If a command is > currently executing at the time of aborting a command, xHC > also generate a command completion event with its completion > code set to Command Abort. When the command ring is stopped, > software may remove, add, or rearrage Command Descriptors. > > The RFT patch is used to cancel command when the above > situation occur. > > To cancel a command, software will initialize a command > descriptor for the cancel command, and add it into a > cancel_cmd_list of xhci. When the command ring is stopped, > software will find the command trbs described by command > descriptors in cancel_cmd_list and modify it to No Op > command. If software can't find the matched trbs, we can > think it had been finished. > > Signed-off-by: Elric Fu <elricfu1@xxxxxxxxx> > Acked-by: Andiry Xu <Andiry.Xu@xxxxxxx> I've NOT acked this patch, just provided some comments for the last version. Please remove this line. Thanks, Andiry -- 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
