On Thu, 25 Sep 2003, Neil Whelchel wrote: > > What kind of endpoints are these? Bulk? > > These are interrupt transfer endpoints, yet anoter jacked up way of doing > things.. (Tons of bus chatter sending empty packets at a syncronous time > base for an asyncronous data protocol.) This thing must have been designed > some close family member of the boss.
Just to comment briefly, if you don't mind... One can imagine reasons for using interrupt endpoints instead of bulk. For example, if this firmware had been ported from a low-speed device to a full-speed device it would make sense, because low-speed doesn't allow bulk transfers. Also, the amount of chatter involved in an interrupt transfer is probably _less_ than the amount involved in a bulk transfer. With interrupt data, the packets are sent only at intervals (rate determined using the "period" given in the endpoint descriptor), until the transfer succeeds. With bulk data, the packets are sent in _every_ frame, maybe even multiple times per frame, until the transfer succeeds. Anyway, it's pointless to complain about synchronous versions of what ought to be asynchronous protocols. It's unavoidable because USB itself is synchronous; everything is defined in terms of frames and micro-frames, and everything is timed by the host controller (not the device controllers). Alan Stern ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
