On Wed, 2012-06-06 at 12:42 -0700, Eric W. Biederman wrote: > Absent anyone even knowing if there are devices that exist that can not > tolerate their bus master bit being flipped when DMA is not ongoing I > think the current state of the code is good. When we find the broken > hardware that can not tolerate a standard PCI bit being used in a > standard way we can add a flag in the core to avoid doing that. > > pci_device_shutdown calls drv->shutdown before calling > pci_device_disable. Which means that only devices that have trouble > with this bit being flipped while DMA is ongoing and don't bother > to stop their own DMA will have a problem. > > As for shifting problems I do think we have shifted the problem in a > very positive way. Now instead of having a random failure at a random > location caused by DMA happing at a random moment for no expected reason > we have failures happening when we disable or enable a device, which > should be much more debugable. That is a very good point. Failure at a predictable point is much better than random failures with the root cause being elsewhere from the point of failure in time and code. This at least gives us a good shot at being able to debug buggy hardware and drivers. -- ==================================================================== Khalid Aziz Unix Systems Lab (970)898-9214 Hewlett-Packard khalid.aziz@xxxxxx Fort Collins, CO -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
