On 2015/3/13 0:08, Rafael J. Wysocki wrote: > On Thursday, March 12, 2015 09:41:21 AM Jiang Liu wrote: >> On 2015/3/12 9:17, Rafael J. Wysocki wrote: >>> On Wednesday, March 11, 2015 10:04:42 PM Luck, Tony wrote: >>>>>> Unfortunately there's a long standing comment in pci_device_remove(): >>>>>> >>>>>> /* >>>>>> * We would love to complain here if pci_dev->is_enabled is set, that >>>>>> * the driver should have called pci_disable_device(), but the >>>>>> * unfortunate fact is there are too many odd BIOS and bridge setups >>>>>> * that don't like drivers doing that all of the time. >>>>>> * Oh well, we can dream of sane hardware when we sleep, no matter how >>>>>> * horrible the crap we have to deal with is when we are awake... >>>>>> */ >>>>>> >>>>>> So, unless we can somehow ignore that comment, I suspect forcing the >>>>>> device to be disabled on driver remove, whether done from pci-core or >>>>>> from x86/pci, is going to cause all sorts of breakage. Are the >>>>>> expectations set by b4b55cda5874 really valid? It seems like something >>>>>> needs to be done to allow the IRQ to be automatically re-established on >>>>>> x86 regardless of the driver doing the right thing when releasing the >>>>>> device. We're still looking at a regression for v4.0 as a result of >>>>>> b4b55cda5874. >>>>> >>>>> In which case we probably should revert commit b4b55cda5874 for the time being. >>>>> >>>>> At least I'd be very nervous about any ad-hoc fixes at this stage of the cycle. >>>> >>>> The comment goes back to the dawn of "git" time ... not sure how much further >>>> back. >>>> >>>> Is this actually still an issue on modern systems? Maybe we need a black list >>>> or white list to separate the good from bad systems? >>> >>> The answer to that is "We don't know" and in my not so humble opinion it is too >>> risky to try to find out at the end of the cycle. >> Hi Rafael and Alex, >> How about a patch which: >> 1) gives a warning if PCI device is still enabled when unloading driver > > That may become sort of noisy. I really would prefer to introduce things like > that by the beginning of the cycle, not by the end of it. Will try this on next merging window. >> 2) release PCI interrupt only if PCI device is disabled. >> By this way, we could support IOAPIC hot-removal on latest platforms and >> avoid regressions on old platforms. > > Well, please submit a patch for discussion. > > I would like to know Bjorn's opinion about that too at least. Still testing the patch, will send it out soon. > > Rafael > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
