On Sat, 4 Sep 2004, Laurent Pinchart wrote: > Hi Alan, > > > That's not right -- at least, it's not right for the first copy of the > > trace that Steve sent out. (I didn't look at the second copy so maybe > > it's different.) In the trace I saw, the first Get-Device-Descriptor asks > > for 64 bytes, not 18. Also, note that there's a port reset in between > > that request and the following Set-Address. > > The first trace seems to be a full-speed USB 1.0 device, while the last one > that Steve sent to me is a low-speed HID device. > > Windows XP asks for 18 bytes for the first Get-Device-Descriptor for low-speed > USB 1.0 (and probably 1.1) devices. You are right about the port reset > though.
Maybe we're talking about different traces. I'm referring to the trace for the Zoom modem (a low-speed device according to Steve), as attached to http://marc.theaimsgroup.com/?l=linux-usb-devel&m=109414499502715&w=2 Here's the first Get-Device-Descriptor request from that trace: frame # 892 f=12001 sync 1776 SOF(xa5) frame 892 crc5 0x2 f=0 f=03865 sync 1784 SETUP(x2d) addr 0 endp 0 crc5 0x2 f=03901 sync 1784 DATA0(xc3) 0x80 0x06 0x00 0x01 0x00 0x00 0x40 0x00 cr?=0x94dd f=04003 sync 1784 ACK(xd2) The value to look at is the 7th data byte in the DATA0 packet: 0x40. This means wLength was 64, not 18. True, in its response the modem said the descriptor length was 18, and in fact it only transmitted the first 8 bytes before getting reset. Nevertheless, the request was for 64 bytes. Frame # 962 shows the second Get-Device-Descriptor request's Setup packet. In that one wLength was equal to 18. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by BEA Weblogic Workshop FREE Java Enterprise J2EE developer tools! Get your free copy of BEA WebLogic Workshop 8.1 today. http://ads.osdn.com/?ad_id=5047&alloc_id=10808&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
