On Thu, 30 Jun 2005 [EMAIL PROTECTED] wrote: > Hello > > I am testing a driver under 2.4.30, that originates from Philips, for > their 1761 OTG high-speed chip. I was verifying drivers behaviour in > error-cases, for which I connecetd a high-speed memory stick over a > looooong cable and a USB analyser.
Implying that you are using the 1761 as a host, not as a slave. > Now, I can pretty easily bring the > controller to a state when it sets the HALT bit in its queue-head. That happens when it receives an error or a STALL token? > The > driver sends -EPIPE back, calls usb_endpoint_halt(), does various cleanup, > everything seems ok, then the (usb-storage?) driver sends BULK_RESET, the > setup packet is ok, but the IN packet is NAKed infinitely. Unforunately a lot of USB Mass Storage devices don't respond correctly to the class-specific reset request. That could easily explain the indefinite NAK. So could your looooong cable. > Now, that is > actually my question. Originally, the driver would just re-validate the > transfer descriptor, waiting for the device to eventually stop NAKing, but > this never happens. So, the driver just spins there, until SCSI / storage > aborts with a timeout. I tried putting a counter for NAK-revalidation > attempts, and completing the URB with an error if the device doesn't > response - but then the higher level retries - and this _forever_. So, the > question is - what is the correct behaviour? Should the driver really just > spin retrying NAKs and wait for higher level timeout (that works, btw), or > should it complete the URB, but there's a bug in storage / SCSI that takes > it to the endless loop? The driver should keep on retrying NAKs. That's what the standard controllers do, and it's why higher levels use timeouts. As for this endless loop -- I can't tell what you're referring to. If you turn on CONFIG_USB_STORAGE_DEBUG, the debugging log will show what's going on at the higher level. Alan Stern ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
