On Sun, 6 Feb 2011, Sujith wrote: > Martin Schleier wrote: > > Interesting, I know that interrupt and bulk endpoints share a lot of > > common logic so I can see how this should work. But is it really > > possible [and more to the point: sane?!] to override the endpoint > > descriptors? > > > > I know that usb_submit_urb checks [when config_usb_debug is enabled] > > if the xfertype of the submitted urb matches the one of the endpoint, > > so I wonder I started to wonder if we are fooling "just" the code > > here, or ourselves in the process? > > > > > ath9k_htc does the same thing (see ath/ath9k/hif_usb.c). > > > It does seem to be working properly but I am wondering if the > > > USB subsystem has to be updated after the driver messes around with bmAttributes. > > > (lsusb would still show the endpoint type as INT). > > > > > > You have a usb_reset_configuration() call before changing > > > the endpoint type, why is that necessary ? And would that > > > reset the endpoints as well ? > > Huh, has this already catched on? > > Well, for ath9k_htc, the FW changes the descriptor type after it is > transferred to the target. The USB devs suggested that usb_device_reset() > should be called by the driver in such cases, but in ath9k_htc's case, > the device is disconnected and the error message "device firmware changed" > is displayed. > > Agreed, this is a dirty hack - but is there any way for a driver to make the USB > subsystem re-configure the endpoints ? Why do you want to? Why does changing the endpoint type from interrupt to bulk improve performance? Yes, the description says that this causes CPU usage to go from 10% to below 1%, but _why_ does it do that? Maybe the same effect can be achieved simply by changing the interrupt interval instead. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
