Hans Petter Selasky schrieb: > On Monday 26 March 2007 16:13, Markus Henschel wrote: >>> Number: 110855 >>> Category: usb >>> Synopsis: ugen: interrupt in msgs are truncated when buffer is full >>> Confidential: no >>> Severity: serious >>> Priority: medium >>> Responsible: freebsd-usb >>> State: open >>> Quarter: >>> Keywords: >>> Date-Required: >>> Class: change-request >>> Submitter-Id: current-users >>> Arrival-Date: Mon Mar 26 14:20:04 GMT 2007 >>> Closed-Date: >>> Last-Modified: >>> Originator: Markus Henschel >>> Release: 6.2 custom kernel >>> Organization: >> Bally Wulff Automaten GmbH >> >>> Environment: >> FreeBSD freebsd-1.bally.de 6.2-RELEASE FreeBSD 6.2-RELEASE #11: Fri Mar 23 >> 21:28:38 CET 2007 >> [EMAIL PROTECTED]:/usr/obj/usr/src/sys/BALLYWULFF i386 >> >>> Description: >> We use ugen for some user space drivers. When an interrupt in endpoint is >> used ugen creates a queue that is filled by the kernel. The user space >> driver is responsible for reading data from the device file. If this >> happens too slow the queue is full and new msgs arriving from the usb >> device are lost. This behavior is OK. >> >> The problem is that the queue is not a multiple of the interrupt in >> endpoints msgs size. So it is possible that the last msg in the queue is >> truncated. This is very hard to detect for a user space driver. The data >> stream seen by the user space driver will contain an incomplete msgs >> directly followed by the next message without knowing truncation happened >> (except when using some data corruption detection mechanism). >> >> It would be much better if ugen would fill the queues of interrupt in >> endpoints until there is no more space for a complete msg. This way the >> user space driver will not loose sync with the incoming msgs. > > The new USB stack has this fixed already. What I do is that the USB driver > stops polling the interrupt endpoint when the user-land application does not > read data. When the user-land application has read a packet, the interrupt > endpoint is started again. The only problem is that some devices, like a > Microsoft mouse I have, stops working immediately when its internal buffer > overflows. Bad hardware design. But if your hardware is not like that, the > new ugen, which is part of the new USB driver, will work great for you. > > Also packet alignment is kept between reads: Only one packet per read. > > See: > > http://www.turbocat.net/~hselasky/usb4bsd > > --HPS >
Thanks, I gave it a try and it seems to work fine :-). Could you please explain how reading an interrupt in endpoint works internally with the new ugen? Is there still a buffer that recieves data from the endpoint or is each read request from user land synchronously triggering a read data request on the interrupt endpoint? Why isn't O_NONBLOCK working anymore? -- Regards, Markus Henschel Development BALLY WULFF Automaten GmbH Maybachufer 48-51 12045 Berlin Phone: +49(30)62002 161 FAX: +49(30)62002 230 http://www.ballywulff.de _______________________________________________ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
