On Thu, Mar 28, 2013 at 11:59 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > > On Thu, Mar 28, 2013 at 8:22 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> >> [+cc Matthew] >> [+cc e1000-devel@xxxxxxxxxxxxxxxxxxxxx for suspected 82575/82598 >> regression] >> >> On Thu, Mar 28, 2013 at 01:24:55PM -0700, Yinghai Lu wrote: >> > patch for Roman >> > >> > On Thu, Mar 28, 2013 at 1:24 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >> > > resending with adding To Roman. >> > > >> > > On Thu, Mar 28, 2013 at 5:46 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >> > > wrote: >> > >> This patch might be *safe*, but it (and the changelog) are completely >> > >> unintelligible. >> > >> >> > >> The problem with applying an unintelligible stop-gap patch is that it >> > >> becomes forever part of the changelog, and it's a huge waste of time >> > >> to everybody who tries to understand the history later. That's why I >> > >> think it's worth spending some time to make a good patch now. >> > > >> > > Please check if attached patch is doing what you want. >> >> Patch inlined below for convenience. >> >> > Subject: [PATCH] PCI: Remove not needed check in disable aspm link >> > >> > Roman reported ath5k does not work anymore on 3.8. >> > Bisected to >> > | commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6 >> > | Author: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx> >> > | Date: Tue Oct 30 15:27:13 2012 +0900 >> > | >> > | PCI/ACPI: Request _OSC control before scanning PCI root bus >> > | >> > | This patch moves up the code block to request _OSC control in order >> > to >> > | separate ACPI work and PCI work in acpi_pci_root_add(). >> > >> > It make pci_disable_link_state does not work anymore as acpi_disabled >> > is set before pci root bus scanning. >> > It will skip that in quirks and pcie_aspm_sanity_check. >> >> I think this regression has nothing to do with pci_disable_link_state(). >> >> When aspm_disabled is set, pci_disable_link_state() doesn't do anything. >> >> In both 3.7 and 3.8, aspm_disabled is set in acpi_pci_root_add() before >> any driver probe routines are run, so it looks like calling >> pci_disable_link_state() from a driver had no effect even in 3.7. This >> is a problem, of course, but not the one Roman is seeing, because ath5k >> calls pci_disable_link_state() from the driver probe routine. >> >> There are also PCI_FIXUP_FINAL quirks for 82575 and 82598 NICs that call >> pci_disable_link_state(). In 3.7, these quirks are run before >> aspm_disabled is set, but 8c33f51d moved the pcie_no_aspm() call up >> before we start scanning the bus, so in 3.8, aspm_disabled is set >> *before* we run them. I think that means 8c33f51d broke all these >> quirks. That's also a problem, of course, but this isn't the one Roman >> is seeing either. >> >> I think the problem Roman is seeing happens when >> pcie_aspm_init_link_state() calls pcie_aspm_sanity_check() during device >> enumeration. In 3.8, the fact that aspm_disabled is already set by the >> time we get here means we skip the check for pre-1.1 PCIe devices, and >> I think *this* is what Roman is seeing. >> >> I suspect the following hunk of your patch is enough to fix things for >> Roman: >> >> > --- linux-2.6.orig/drivers/pci/pcie/aspm.c >> > +++ linux-2.6/drivers/pci/pcie/aspm.c >> > @@ -493,15 +492,6 @@ static int pcie_aspm_sanity_check(struct >> > return -EINVAL; >> > >> > /* >> > - * If ASPM is disabled then we're not going to change >> > - * the BIOS state. It's safe to continue even if it's a >> > - * pre-1.1 device >> > - */ >> > - >> > - if (aspm_disabled) >> > - continue; >> > - >> > - /* >> > * Disable ASPM for pre-1.1 PCIe device, we follow MS to >> > use >> > * RBER bit to determine if a function is 1.1 version >> > device >> > */ >> >> However, this test was added by Matthew in c9651e70, and I can't remove >> it unless we have an explanation of why removing it will not reintroduce >> the bug he was fixing. >> >> This code is such a terrible mess that it's not surprising at all that >> we have all these issues. But there's too much to untangle in v3.9; all >> we can hope for is to fix the regressions in v3.9 and clean it up later. > > > v1 will fix quirks and pcie_aspm_sanity_check path. > v2. will go further even user pass "aspm=off", those quirks and disable aspm > in driver > will still work, and also call pcie_no_aspm for disable aspm for FADT path > early. > > So now you want half of v1, and not want to fix quirk path. > Is my understanding right? What I want is a patch that fixes the regression and doesn't break anything else, along with a changelog that makes it obvious that we're doing the right thing. I don't know what that looks like yet. None of your patches so far is even close. Half of your v1 patch (removing the pcie_aspm_sanity_check() test) *might* be the right thing, but only if you can clearly explain why that will not reintroduce the bug Matthew fixed with c9651e70. I think we also need to fix the PCI_FIXUP_FINAL quirk regression, but that's a separate issue and should be a separate patch. -- 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
