On Wed, Mar 01, 2006 at 04:56:51PM -0800, Pete Zaitcev wrote: > On Wed, 1 Mar 2006 16:27:56 -0800, Marc Singer <[EMAIL PROTECTED]> wrote: > > > 0:15.261198 # 10 S Ci 009:00 s 80 00 0000 0000 0002 ( DtH st dv GET_STATUS > > ) --- 2 < > > 0:15.261201 # 11 S Ci 009:00 s 80 06 0600 0000 000a ( DtH st dv > > GET_DESCRIPTOR [DEVICE_QUALIFIER 0] ) --- 10 < > > ... > > 0:15.261981 # 10 C Ci 009:00 --- 0 2 = 0100 > > 0:15.261982 # 10 S Ci 009:00 s 80 00 0000 0000 0002 ( DtH st dv GET_STATUS > > ) --- 2 < > > 0:15.261988 # 11 C Ci 009:00 --- -32 0 > > > > I interpret this to mean that the device is asking the host for the > > device status and then a DEVICE_QUALIFIER descriptor. It returns > > 0x0100. The device turns around and asks for it again. The host then > > returns an error, -EPIPE, for that URB. Am I understanding this flow > > correctly? > > Device cannot ask host anything in USB. It just sits there quietly and > waits to be polled. Always.
Right. So the host is asking the device for the DEVICE status and then for the DEVICE_QUALIFIER descriptor. The device sends the status indicating that it's self-powered. Its response to #11 is what is broken. It may be getting confused by the second status request *or* it may have sent the STALL (is that the -32?) before it received the second GET_STATUS. > So, in the above exchange, host performs two control transfers. > The log seems to be post-processed by some tool, which dropped interesting > information such as URB tag. The URB tag is recoded as a number prefixed with #. It makes it easier to correlate the messages. Do the URB tags have implicit information in them? The numbers on the left may be manufactured > from the tag. If so, it appears that the host > - submits GET_STATUS > - submits GET_DESCRIPTOR > - receives status > - submits another GET_STATUS > - receives a stall for GET_DESCRIPTOR > > So, the control transfers are queued. Are you sure that it's a sane > thing to do? So, where exactly is the STALL in the above exchange? I suspect that the UDC driver has lost its state and is sending a STALL because it doesn't know what it is doing. Here is the raw data. I don't believe that the annotated version dropped anything important and it's easier for a human like me to read. e2372540 1594541797 S Ci:009:00 s 80 00 0000 0000 0002 2 < e23725c0 1594541800 S Ci:009:00 s 80 06 0600 0000 000a 10 < ... e2372540 1594542580 C Ci:009:00 0 2 = 0100 e2372540 1594542581 S Ci:009:00 s 80 00 0000 0000 0002 2 < e23725c0 1594542587 C Ci:009:00 -32 0 ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
