On Wed, 9 Nov 2005, Daniel Drake wrote: > Hi, > > I'm attempting to get started on a new driver for a fingerprint sensor. > > I've sniffed some data but there are a few things in the logs which are > confusing. > > The descriptor of the interface I'm working with:
<...> > URB 12 (see attachment) has RequestTypeReservedBits set to 0x40. With other > devices I usually see this as 0 (even though the actual RequestType would be > 0x40). What does this mean? I guess its irrelevant. Probably. I have no idea what all these flags and things mean; they must be part of the Windows USB API. At any rate, only the actual contents of the Setup packet really matter. > URB 13 is the more interesting one. > > It deals with endpoint 0x82, which the descriptor shows as a Bulk In > endpoint, > but the log shows 64kb of data being sent to this endpoint with direction > *out*. > > And the response isn't recieved instantly either (almost like it is an > interrupt endpoint?) - about 20 more URBs bounce around before URB 13 comes > back. When it comes back, it has direction *in* and also comes with 64kb of > data. > > Is this non-standard behaviour, or do I need to read more about USB to get my > head around this? The behaviour that I'm familiar with on other devices is > where an urb is sent to a bulk in endpoint with no data and direction in, and > a result is recieved immediately after with direction in and a payload of > data. I doubt very much that this is non-standard behavior. Probably you're just seeing a peculiarity in the way that UsbSnoop works (or the way Windows works). Regardless of whatever bits happen to be set in the log, it's clear that endpoint 0x82 is _always_ going to be an IN endpoint. I do know that for some strange reason UsbSnoop insists on dumping the contents of the transfer buffer in both the "down" and "up" reports -- in spite of the fact that the "down" values are unimportant for IN transfers and the "up" values are unimportant for OUT transfers. The time delay could simply mean the device wasn't ready to send the IN data right away. Alan Stern ------------------------------------------------------- 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
