On Fri, 21 May 2004, David Brownell wrote: > Guennadi Liakhovetski wrote: > > > > Hence the main question - what could this BUG mean? > > Usually it means that the HCD freed a TD before the HC was > quite done with it ... so the HC put it on the donelist, > and donelist processing tried to find the TD given its > DMA address (using that routine), then BUG(). > > There are some fairly non-obvious races that can cause that, > and even the 2.6 code had a bug in that area that was only > fixed in 2.6.5 or so ... which bug will certainly be in the > 2.4 usb-ohci code, it came from there. That one involved > the "unlink empty ED" case taking an inappropriate shortcut; > it really needs to wait a frame like all the other cases. > (However, the usb-ohci "wait a frame" logic is broken too, > in ways that showed up mostly on slower systems. I think a > PXA would hit those bugs often enough.)
Ok, thanks. Then, 2 other questions - can these races or some other bugs in ohci also explain why the driver works fine on the PCI-controller internal OHCI chip and doesn't work so well on the cardbus USB2.0 card? I also tried a PCI USB card with 4 ports (OHCI too). And that one produced quite funny results: on the first power-on the kernel boots as far as up to "freeing init memory". After a reboot it gets a couple lines further. 2 more reboots and you get a prompt, which works for some time (a couple of seconds / minutes) - if I have ohci hard linked in the kernel... Then the system just hangs. If I compile USB as modules, the system hangs as soon as I load usb-ohci-pci. A number on network cards in the same PCI slot work fine. Besides, I tried one more CardBus card - a Xircom ethernet card, which also has problems - after some time / amount of data transferred, the network starts to lose packets. So, it looks like the problem is not (or, at least, not only) in the ohci driver. Rather - from the USB-OHCI point of view, which PCI / DMA / CardBus / ... problems can lead to this BUG in dma_to_ed_td? Thanks Guennadi --------------------------------- Guennadi Liakhovetski, Ph.D. DSA Daten- und Systemtechnik GmbH Pascalstr. 28 D-52076 Aachen Germany ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
