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[Xen-devel] [PATCH]UHC should not generate interrupt when USB device returns NAK

  • To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Huang, Xinmei" <xinmei.huang@xxxxxxxxx>
  • Date: Tue, 5 Dec 2006 12:48:34 +0800
  • Delivery-date: Mon, 04 Dec 2006 20:50:37 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AccYIFUctQo+acaFStST+nWBI8j1CgABvJGgAABFGDA=
  • Thread-topic: [PATCH]UHC should not generate interrupt when USB device returns NAK

This patch adds support for USB mouse/tablet status check and restricts
Universal Host Controller interrupt generating when receiving NAK in
interrupt transfer.

According to usb spec, USB mouse/tablet device returns NAK to host
controller if its status does not alter in interrupt transfer.
And UHC should leave a TD active when receiving NAK and execute this
incompleted TD in a subseqent frame. 
UHC only generates an interrupt on complete after the TD with ICO bit=1
is completed.

This patch obliges UHC & USB mouse/tablet to behave consistently with

Signed-off-by: Xinmei Huang <xinmei.huang@xxxxxxxxx>

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