Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932240Ab3HWWFY (ORCPT ); Fri, 23 Aug 2013 18:05:24 -0400 Received: from mail-ie0-f179.google.com ([209.85.223.179]:53038 "EHLO mail-ie0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756463Ab3HWWFV (ORCPT ); Fri, 23 Aug 2013 18:05:21 -0400 MIME-Version: 1.0 In-Reply-To: <4634097.MXvnqpQKZr@vostro.rjw.lan> References: <1377278379-9054-1-git-send-email-nhorman@tuxdriver.com> <3958698.Gm9Wz19SSi@vostro.rjw.lan> <4634097.MXvnqpQKZr@vostro.rjw.lan> From: Bjorn Helgaas Date: Fri, 23 Aug 2013 16:04:59 -0600 Message-ID: Subject: Re: [PATCH] ACPI: Fix osc flag setup ordering to allow pcie hotplug use when available To: "Rafael J. Wysocki" Cc: Neil Horman , "linux-kernel@vger.kernel.org" , Len Brown , "linux-acpi@vger.kernel.org" , Yinghai Lu , Linux PCI Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7354 Lines: 157 On Fri, Aug 23, 2013 at 3:40 PM, Rafael J. Wysocki wrote: > On Friday, August 23, 2013 02:46:23 PM Bjorn Helgaas wrote: >> On Fri, Aug 23, 2013 at 2:53 PM, Rafael J. Wysocki wrote: >> > On Friday, August 23, 2013 04:05:11 PM Neil Horman wrote: >> >> On Fri, Aug 23, 2013 at 09:38:18PM +0200, Rafael J. Wysocki wrote: >> >> > [CCs added] >> >> > >> >> > Please always send PCI-related material to linux-pci in the first place. >> >> > >> >> Sorry, I ran get_maintainers and it seemed to think linux-acpi was sufficient. >> >> >> >> > The change that broke things for you was actually intentional: >> >> > >> >> > commit b8178f130e25c1bdac1c33e0996f1ff6e20ec08e >> >> > Author: Bjorn Helgaas >> >> > Date: Mon Apr 1 15:47:39 2013 -0600 >> >> > >> >> > Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus" >> >> > >> >> > This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6. >> >> > >> >> > so I think we'll need to clean up the ASMP initialization after all. >> >> > >> >> Crud. Reading over the revert commit, it seems like the problem boils down to >> >> the odering of checking aspm_disabled. It seems to me that the simple fix is to >> >> track the desire for acpi to disable aspm separately from the users desire to >> >> disable aspm (aspm_disabled). Then we just turn the points where we check the >> >> aspm_disabled into the appropriate or of two variables, except for >> >> pcie_asmp_sanity_check, which remains sensitive to just the user disable option. >> >> >> >> Or is there more to this? >> > >> > No, I think you're right. >> > >> > Bjorn, what do you think? >> >> My opinion is that the _OSC/ASPM state management is ridiculously >> complicated already, and this would make it slightly more complicated. >> That's why my preference would be to attempt a more radical cleanup >> and simplification instead of adding another wart. > > Well, do you have anything specific in mind? If I had a specific fix in mind, I would just post it, but I've never had time to work through it all. What I mean by complicated is that every time I have to look at ASPM, I have to start by trying to figure out the relationships between these variables: aspm_policy # default 0 (POLICY_DEFAULT) or POLICY_PERFORMANCE or POLICY_POWERSAVE depending on config aspm_disabled # default 0 aspm_force # default 0 aspm_support_enabled # default true plus the _OSC-related code in acpi_pci_root_add(), which honestly is a rat's nest. It sounds like Neil's fix (while probably correct) would tangle that nest a little more. But I guess it would make sense to see the actual patch and the justification (a regression fix, I suppose, but the details weren't clear to me) before deciding. >> >> > On Friday, August 23, 2013 01:19:39 PM Neil Horman wrote: >> >> > > Somewhere between 3.9 and 3.10 it seems the order in which pcie and acpi probed >> >> > > slots for hotplug capabilites got reversed. While this isn't a big deal, it did >> >> > > uncover a bug in the ACPI bus setup path. Specifically, acpi_pci_root_add calls >> >> > > pci_acpi_scan_root before setting the osc flags for the device handle. >> >> > > pci_acpi_scan_root, among other things uses device_is_managed_by_native_pciehp() >> >> > > to determine if a given slot has pcie hotplug capabilties, whcih checks the >> >> > > devices OSC_PCI_EXPRESS_NATIVE_HP_CONTROL flag. Since that flag is not set >> >> > > until after pci_acpi_scan_root_completes, the acpi code never sees that pcie >> >> > > slots are hotplug capable and configures them all to use acpi instead. >> >> > > >> >> > > Fix is pretty simple, just defer the scan until after the osc flags have been >> >> > > set on the device. Tested by myself and it seems to work well. >> >> > > >> >> > > Signed-off-by: Neil Horman >> >> > > CC: Len Brown >> >> > > CC: "Rafael J. Wysocki" >> >> > > CC: linux-acpi@vger.kernel.org >> >> > > --- >> >> > > drivers/acpi/pci_root.c | 41 ++++++++++++++++++++--------------------- >> >> > > 1 file changed, 20 insertions(+), 21 deletions(-) >> >> > > >> >> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c >> >> > > index 5917839..a2c2661 100644 >> >> > > --- a/drivers/acpi/pci_root.c >> >> > > +++ b/drivers/acpi/pci_root.c >> >> > > @@ -437,27 +437,6 @@ static int acpi_pci_root_add(struct acpi_device *device, >> >> > > flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT; >> >> > > acpi_pci_osc_support(root, flags); >> >> > > >> >> > > - /* >> >> > > - * TBD: Need PCI interface for enumeration/configuration of roots. >> >> > > - */ >> >> > > - >> >> > > - /* >> >> > > - * Scan the Root Bridge >> >> > > - * -------------------- >> >> > > - * Must do this prior to any attempt to bind the root device, as the >> >> > > - * PCI namespace does not get created until this call is made (and >> >> > > - * thus the root bridge's pci_dev does not exist). >> >> > > - */ >> >> > > - root->bus = pci_acpi_scan_root(root); >> >> > > - if (!root->bus) { >> >> > > - dev_err(&device->dev, >> >> > > - "Bus %04x:%02x not present in PCI namespace\n", >> >> > > - root->segment, (unsigned int)root->secondary.start); >> >> > > - result = -ENODEV; >> >> > > - goto end; >> >> > > - } >> >> > > - >> >> > > - /* Indicate support for various _OSC capabilities. */ >> >> > > if (pci_ext_cfg_avail()) >> >> > > flags |= OSC_EXT_PCI_CONFIG_SUPPORT; >> >> > > if (pcie_aspm_support_enabled()) { >> >> > > @@ -520,6 +499,26 @@ static int acpi_pci_root_add(struct acpi_device *device, >> >> > > "(_OSC support mask: 0x%02x)\n", flags); >> >> > > } >> >> > > >> >> > > + /* >> >> > > + * TBD: Need PCI interface for enumeration/configuration of roots. >> >> > > + */ >> >> > > + >> >> > > + /* >> >> > > + * Scan the Root Bridge >> >> > > + * -------------------- >> >> > > + * Must do this prior to any attempt to bind the root device, as the >> >> > > + * PCI namespace does not get created until this call is made (and >> >> > > + * thus the root bridge's pci_dev does not exist). >> >> > > + */ >> >> > > + root->bus = pci_acpi_scan_root(root); >> >> > > + if (!root->bus) { >> >> > > + dev_err(&device->dev, >> >> > > + "Bus %04x:%02x not present in PCI namespace\n", >> >> > > + root->segment, (unsigned int)root->secondary.start); >> >> > > + result = -ENODEV; >> >> > > + goto end; >> >> > > + } >> >> > > + >> >> > > pci_acpi_add_bus_pm_notifier(device, root->bus); >> >> > > if (device->wakeup.flags.run_wake) >> >> > > device_set_run_wake(root->bus->bridge, true); >> >> > > >> >> >> > -- >> > I speak only for myself. >> > Rafael J. Wysocki, Intel Open Source Technology Center. > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/