On Fri, May 11, 2007 at 09:58:15AM -0400, Alan Stern wrote: > On Thu, 10 May 2007, Greg KH wrote: > > > On Fri, May 04, 2007 at 11:56:18AM -0400, Alan Stern wrote: > > > From: Danny Budik <[EMAIL PROTECTED]> > > > > > > This patch (as899) adds a new ioctl to usbfs: USBDEVFS_GETFRAMENUM. > > > It allows user programs to obtain the current Start-Of-Frame number on > > > a USB bus. > > > > > > Note that the values returned by the get_frame method in the various > > > host controller drivers are not consistent. They should be adjusted > > > so that they provide the actual frame number as it appears on the bus; > > > that is, a number incrementing by one every millisecond, ranging from 0 > > > to 2047. That will have to be done separately; it interacts with the > > > start_frame values used for submitting Isochronous URBs. > > > > > > Signed-off-by: Alan Stern <[EMAIL PROTECTED]> > > > > As this value will be wrong, and will be out-of-date due to timing > > issues going to userspace and back, I still don't see the use of adding > > this to our kernel at this point in time. > > Okay, I'll fix up the HCDs and make them return consistent values first. > Then I'll resubmit the patch.
Ok, that sounds good. > The argument about the value being out-of-date because of timing issues > doesn't hold water. The same argument applies to gettimeofday(2), but > Unix systems have supported that call for a very long time. I thought that you needed to do something with this value pretty quickly, and that by the time you were able to send something back into the kernel, the value would be not correct anymore. But if this is really just like a timestamp, then ok, I have no objection other than it needs to be correct for all host controllers. thanks, greg k-h ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
