Hi, Is there a function in the Linux USB API that converts a given number of milliseconds into a given number of isochronous frames? I see many Linux drivers, like the USB video class one, that could need to dynamically adjust the number of buffered isochronous frames depending on the device speed and endpoint descriptor. For example: FULL speed USB uses 1000 FPS SUPER + HIGH speed USB uses 1000 - 8000 FPS, in power of 2 steps typically. uvcvideo.h ... #define UVC_URBS 5 #define UVC_MAX_PACKETS 32 The problem is that all Linux USB drivers using isochronous transfers use a fixed amount of buffering which gives a variable amount of buffering time, because the frames per second is a variable. For the uvc driver my point is that at HIGH speed the buffering is 5 * 4ms. At FULL speed it is 5 * 32ms. At HIGH speed I would like to increase the buffering a little bit to avoid high IRQ rates and at FULL speed I would like to reduce the buffering a bit. --HPS -- 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
