On Thu, 22 Sep 2005, Cristian Chiarello wrote:
> Hi @ all. > I'm working on a custom EP7311 board with isp1161A1 and linux-2.4.21-rmk1. > Another people have made porting of kernel to this board but now I have > problem with data tranfert in ISO mode with a webcam logitech > 4000pro: some frame is often loss. The driver I use I think is the same > mentioned in this thread: > http://sourceforge.net/mailarchive/message.php?msg_id=665283 isp1161 is a full speed device, i.e., it supports (theoretically) transfer rates up to 12Mbit/s. I don't know your webcam, but supposing for the sake of example that it is trying to output "quarter" PAL resolution, 25fps, YUV 4:2:0 (i.e., 12 bit per pixel in average) would yield 352*288*25*12 = 30412800 bit/s > 12Mbit/s > I'm a bit confuse about ISO support in 1161A1. > In yours page I have readed that 116x not support ISO tranfers but between the > features of 1161A1 there is: > "Endpoints with double buffering to increase throughput and ease real-time > data transfer for both DC transfers and HC isochronous (ISO) transactions". 116x hardware is capable of iso transfers. Whether these transfers are supported or not, depends on the driver. The driver included in the 2.6 kernels does not support iso transfers. The main reason it doesn't is that nobody has asked for this feature. Except until 2 weeks ago someone asked about it. There are other reasons too, including full speed transfer rate's inadequacy for video as explained above. Olav PS. I was just finishing this e-mail, when a new one arrived from you. The driver's name is isp116x-hcd, because it handles both isp1160 and isp1161 chip variants, including your A1 chip. But no iso transfers, sorry. ------------------------------------------------------- SF.Net email is sponsored by: Tame your development challenges with Apache's Geronimo App Server. Download it for free - -and be entered to win a 42" plasma tv or your very own Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
