On Thu, 27 May 2010, Matthew Garrett wrote: > On Wed, May 26, 2010 at 06:14:52PM -0400, Alan Stern wrote: > > > We don't have to worry about that. If the hardware is broken and the > > kernel doesn't realize it, the user will just have to tell it not to > > allow runtime suspend for those devices. > > It's worse than that - Windows simply doesn't use legacy PCI PMEs for > anything, so an increasing number of modern machines don't have them > wired up. Defaulting to runtime PM simply isn't practical, since the > behaviour will simply be that the devices stop working without any > indication that they've stopped working. Tell me about it! The situation in USB is at least as bad... > The "easiest" workaround would > be a thread that polls for PCI devices with set PME bits, along with a > set of heuristics for determining whether the device can really wake up. ... and no such workaround is possible with USB. > Devices in the core logic (like USB generally is) will be fine in any > case. It's discrete PCI devices that are the problem. In any case, I assume we'll continue to initialize devices with "forbidden" status and require userspace (or drivers that have special information) to explicitly allow runtime PM. Alan Stern -- 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
