On Tue, 29 Mar 2005, Nikhil Bhargava wrote: > hi all, > > I have a basic doubt regarding mamping for user data on a usb packet. I am > working on kernel > 2.4.20.In this there is no provision of bandwidth checking so all data could > be send in one big > packet. > > I wish to know that suppose i have a ping packet of 35k, then how it is send > on a usb bus using
You can't send packets of length 35 KB. No packet is allowed to be larger than 1024 bytes. > A Iso pipe With iso pipes you tell the kernel how to divide your data up into packets when you submit an URB. See the definition of struct usb_iso_packet_descriptor. > B Bulk pipe With bulk pipes the kernel divides the data up into packets for you. Each packet is the maximum size allowed for the endpoint, except possibly the last one which might be smaller. > I mean into what size itis broken up and how many packets are formed. Then > how many packets are > combine dto form a frame and how much data goes in single urb. That would > tell me how many urbs > are allocated for it. Generally a frame contains as many packets as will fit. You can put as much data in a single URB as you like. Note that URBs are allocated by _you_, not by the kernel. Alan Stern ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
