Lonnie Mendez wrote:
Perhaps tweaking the value of ep_bInterval for the tablet's status
change endpoint would help? The endpoint descriptor for the tablet
currently has this at 3 milliseconds. The hid mouse reports a 10
millisecond polling interval.
Indeed. I'm not quite sure how or why I did that in the 1st place as the tablet started life as a
copy of the mouse in any case.
I've had good drag through the specs and all the data sheets for mouse chips I could find out there
and most of them seem to recommend a value no faster than 8ms.
This drops the cpu utilisation of a Windows guest while idle about 75% when
using -usbdevice tablet
I've not noticed any change in usability or mouse responsiveness.
(I played with values up to 0xFF but after about 0x20 there seemed to be
immeasurable/no difference)
Index: hw/usb-hid.c
===================================================================
RCS file: /cvsroot/qemu/qemu/hw/usb-hid.c,v
retrieving revision 1.5
diff -u -r1.5 usb-hid.c
--- hw/usb-hid.c 19 Jul 2006 18:06:15 -0000 1.5
+++ hw/usb-hid.c 24 Jul 2006 09:55:22 -0000
@@ -169,7 +169,7 @@
0x81, /* u8 ep_bEndpointAddress; IN Endpoint 1 */
0x03, /* u8 ep_bmAttributes; Interrupt */
0x08, 0x00, /* u16 ep_wMaxPacketSize; */
- 0x03, /* u8 ep_bInterval; (255ms -- usb 2.0 spec) */
+ 0x20, /* u8 ep_bInterval; (255ms -- usb 2.0 spec) */
Brad
--
"Human beings, who are almost unique in having the ability
to learn from the experience of others, are also remarkable
for their apparent disinclination to do so." -- Douglas Adams
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