> From: Matthew Dharm [mailto:[EMAIL PROTECTED]] > > Most likely, the device is busy doing other things. While you are > guaranteed bus bandwidth, you are not guaranteed to have a responsive > device. > > On Wed, Jun 07, 2000 at 11:27:28AM -0300, Claudio Matsuoka wrote: > > > > What would you point as the most likely cause for a > usb_control_msg() > > returning -ETIMEDOUT? Shouldn't control transfers be given > a guaranteed > > bus allocation? > > > > In this case an isochronous transfer (from the OV511) is > taking place. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Isoc and interrupt transfers are guaranteed to have access to 90% of the bus time. The remaining 10% is left for control transfers. At full speed (12 Mbps), this is 3 transfers per frame (USB 1.1 spec, page 39). If there's any bus time remaining after the control messages, then bulk transfers may be done. However, since we currently don't have any bandwidth allocation/management, there is nothing that is enforcing this behavior. It could be that the isoc camera transfers are consuming so much bandwidth that nothing else can be done on the bus. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ My current plan is to focus on bandwidth allocation/mgt (and support for the USB PlugFest in August) and let other people focus on USB driver autoloading etc., although I would like to be actively involved in this also. This could change if some there is some other help on USB PlugFest support (specs, test software). I think that these 2 areas are where we need to concentrate our efforts (along with the usual HCD and device driver problems). ~Randy ___________________________________________________ |Randy Dunlap Intel Corp., DAL Sr. SW Engr.| |randy.dunlap.at.intel.com 503-696-2055| |NOTE: Any views presented here are mine alone | |and may not represent the views of my employer. | |_________________________________________________| --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
