On Wed, Mar 27, 2013 at 6:43 PM, B, Ravi <ravibabu@xxxxxx> wrote: > Hi > > I am observing issue while streaming video from usb camera connected to host controller based on mentor graphics. The issue is root caused that there are huge SOF gaps seen between the two isochronous IN token issued by host controller. This is due to fact, significant amount of time is spent in uvc callback function handler. Due to this next request programmed is delayed leads to this failure of video streaming. I have measured time taken by uvc callback function is in range minimum of 11 microsecond to maximum of 3318 microsecond. Looks like callback handler doing If you are playing ARM and I remember correctly, it is quite slow to read coherent memory from CPU, but writing is OK because of store buffer. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
