On Fri, 29 Sep 2006, Rumjantsev Egor wrote: > Hello. > I develop driver for USB 2.0 camera. It has 2 IN endpoints with > MaxPacketSize 512 bytes. > I need to read stream of video data about 28 Mb/s. I use 4 urb in queue > for each endpoint's stream. The main trouble is that if the amount of > data which i need to read in one URB divide on 512 without any rest then > data transfer works fine. But if a size of URB not divide on 512 without > rest part i receive EOVERFLOW error. > for example - size of URB was 1854 and in URB's callback function i see > that urb->actual_length = 1536. > Are there some ideas about this trouble ?
Do you know the size of the packets the camera sends? Are they all 512 bytes? EOVERFLOW means that a packet was received and was too large to fit in your URB's buffer. For example, if you URB's size if 1854 then it can hold three 512-byte packets plus a fourth packet with <= 318 bytes. But if the camera sends four packets each with 512 bytes then the last one will overflow your URB. To be safe, make your URB's size always a multiple of 512. Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
