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Date: Tue, 02 Apr 2013 02:10:31 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Yinghai Lu <yinghai@...nel.org>,
Roman Yepishev <roman.yepishev@...il.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Taku Izumi <izumi.taku@...fujitsu.com>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Matthew Garrett <matthew.garrett@...ula.com>,
"e1000-devel@...ts.sourceforge.net"
<e1000-devel@...ts.sourceforge.net>
Subject: Re: [PATCH] PCI: Remove not needed check in disable aspm link
On Monday, April 01, 2013 05:52:56 PM Bjorn Helgaas wrote:
> On Fri, Mar 29, 2013 at 11:04:48AM -0700, Yinghai Lu wrote:
> > attatched -v3 again
> >
> > On Fri, Mar 29, 2013 at 11:02 AM, Yinghai Lu <yinghai@...nel.org> wrote:
> > > On Fri, Mar 29, 2013 at 5:24 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> > >>
> > >> 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.
> > >
> > >
> > > First commit from Matthew
> > > 0ae5eaf10 PCI: ignore pre-1.1 ASPM quirking when ASPM is disabled
> > > Right now we won't touch ASPM state if ASPM is disabled, except in the case
> > > where we find a device that appears to be too old to reliably support ASPM.
> > > Right now we'll clear it in that case, which is almost certainly the wrong
> > > thing to do
> > >
> > > Try to not touch pre-1.1 ASPM for all, and it causes lots of regression.
> > >
> > > So second commit
> > >
> > > cdb0f9a1ad2e ASPM: Fix pcie devices with non-pcie children
> > > Since 3.2.12 and 3.3, some systems are failing to boot with a BUG_ON.
> > > Some other systems using the pata_jmicron driver fail to boot because no
> > > disks are detected. Passing pcie_aspm=force on the kernel command line
> > > works around it.
> > >
> > > move the check aspm_disabled down.
> > >
> > > but ath5 and etc (pre-1.1) really need to aspm_disable to change their
> > > hw setting.
> > >
> > > So the right solution would be dropping pcie_aspm_sanity_check()
> > > change -in v2 should make all both happy, as quirk and disable that in
> > > driver for ath5 are calling
> > > pcie_disable_aspm_state explicitly.
> > >
> > > In v2, we already removed pcie_clear_aspm() that is calling
> > > pcie_disable_aspm_state.
> > >
> > >
> > > Please check attached -v3.
>
> It's getting late in the v3.9 cycle already, and while your v3 patch
> probably fixes Roman's problem, I can't convince myself that it is
> safe in general.
>
> I think the safest thing to do at this point is to revert 8c33f51df
> ("PCI/ACPI: Request _OSC control before scanning PCI root bus") with a
> patch like the one below.
>
> That does mean the booting path and hotplug paths will be different (we set
> aspm_disabled after boot but before hotplug), but it was that way for a
> long time before 8c33f51df. I think it's more important to fix this recent
> ath5k regression than to fix a long-standing hotplug bug that nobody ever
> complained about.
>
> Obviously, I think we should fix the hotplug bug and clean up the ASPM
> mess, too. But we need to do that when we have more time to do it right
> and test it.
>
> Bjorn
>
>
> commit 96e5d01cd536458435ef0678d9fa3dc542afb41f
> Author: Bjorn Helgaas <bhelgaas@...gle.com>
> Date: Mon Apr 1 15:47:39 2013 -0600
>
> Revert "PCI/ACPI: Request _OSC control before scanning PCI root bus"
>
> This reverts commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6.
>
> Conflicts:
> drivers/acpi/pci_root.c
>
> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=55211
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 0ac546d..c740364 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -415,7 +415,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
> struct acpi_pci_root *root;
> struct acpi_pci_driver *driver;
> u32 flags, base_flags;
> - bool is_osc_granted = false;
>
> root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
> if (!root)
> @@ -476,6 +475,30 @@ 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.
> + */
> +
> + mutex_lock(&acpi_pci_root_lock);
> + list_add_tail(&root->node, &acpi_pci_roots);
> + mutex_unlock(&acpi_pci_root_lock);
> +
> + /*
> + * 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) {
> + printk(KERN_ERR PREFIX
> + "Bus %04x:%02x not present in PCI namespace\n",
> + root->segment, (unsigned int)root->secondary.start);
> + result = -ENODEV;
> + goto out_del_root;
> + }
> +
> /* Indicate support for various _OSC capabilities. */
> if (pci_ext_cfg_avail())
> flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
> @@ -494,6 +517,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
> flags = base_flags;
> }
> }
> +
> if (!pcie_ports_disabled
> && (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) {
> flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
> @@ -514,54 +538,28 @@ static int acpi_pci_root_add(struct acpi_device *device,
> status = acpi_pci_osc_control_set(device->handle, &flags,
> OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
> if (ACPI_SUCCESS(status)) {
> - is_osc_granted = true;
> dev_info(&device->dev,
> "ACPI _OSC control (0x%02x) granted\n", flags);
> + if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
> + /*
> + * We have ASPM control, but the FADT indicates
> + * that it's unsupported. Clear it.
> + */
> + pcie_clear_aspm(root->bus);
> + }
> } else {
> - is_osc_granted = false;
> dev_info(&device->dev,
> "ACPI _OSC request failed (%s), "
> "returned control mask: 0x%02x\n",
> acpi_format_exception(status), flags);
> + pr_info("ACPI _OSC control for PCIe not granted, "
> + "disabling ASPM\n");
> + pcie_no_aspm();
> }
> } else {
> dev_info(&device->dev,
> - "Unable to request _OSC control "
> - "(_OSC support mask: 0x%02x)\n", flags);
> - }
> -
> - /*
> - * TBD: Need PCI interface for enumeration/configuration of roots.
> - */
> -
> - mutex_lock(&acpi_pci_root_lock);
> - list_add_tail(&root->node, &acpi_pci_roots);
> - mutex_unlock(&acpi_pci_root_lock);
> -
> - /*
> - * 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) {
> - printk(KERN_ERR PREFIX
> - "Bus %04x:%02x not present in PCI namespace\n",
> - root->segment, (unsigned int)root->secondary.start);
> - result = -ENODEV;
> - goto out_del_root;
> - }
> -
> - /* ASPM setting */
> - if (is_osc_granted) {
> - if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM)
> - pcie_clear_aspm(root->bus);
> - } else {
> - pr_info("ACPI _OSC control for PCIe not granted, "
> - "disabling ASPM\n");
> - pcie_no_aspm();
> + "Unable to request _OSC control "
> + "(_OSC support mask: 0x%02x)\n", flags);
> }
>
> pci_acpi_add_bus_pm_notifier(device, root->bus);
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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