Re: [PATCH][RFC v3] PCI: Workaround to enable poweroff on Mac Pro 11

[Bjorn Helgaas]

On Fri, Aug 19, 2016 at 04:30:25PM +0800, Chen Yu wrote:
> People reported that they can not do a poweroff nor a
> suspend to ram on their Mac Pro 11. After some investigations
> it was found that, once the PCI bridge 0000:00:1c.0 reassigns its
> mm windows to ([mem 0x7fa00000-0x7fbfffff] and
> [mem 0x7fc00000-0x7fdfffff 64bit pref]), the region of ACPI
> io resource 0x1804 becomes unaccessible immediately, where the
> ACPI Sleep register is located, as a result neither poweroff(S5)
> nor suspend to ram(S3) works.
> 
> As suggested by Bjorn, further testing shows that, there is an
> unreported device may be (using) conflict with above aperture,
> which brings unpredictable result such as the failure of accessing
> the io port, which blocks the poweroff(S5). Besides if we reassign
> the memory aperture to the other place, the poweroff works again.
> 
> As we do not find any resource declared in _CRS which contain above
> memory aperture, and Mac OS does not use this pci bridge neither, we
> choose a simple workaround to clear the hotplug flag(suggested by
> Yinghai Lu), thus do not allocate any resource for this pci bridge,
> and thereby no conflict anymore.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=103211
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> Cc: Lukas Wunner <lukas@xxxxxxxxx>
> Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> ---
>  drivers/pci/quirks.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 37ff015..04bbdba 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2776,6 +2776,26 @@ static void quirk_hotplug_bridge(struct pci_dev *dev)
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_HINT, 0x0020, quirk_hotplug_bridge);
>  
>  /*
> + * Apple: Avoid programming the memory/io aperture of 00:1c.0
> + *
> + * BIOS does not declare any resource for 00:1c.0, but with
> + * hotplug flag set, thus the OS allocates:
> + * [mem 0x7fa00000 - 0x7fbfffff]
> + * [mem 0x7fc00000-0x7fdfffff 64bit pref]
> + * which is conflict with an unreported device, which
> + * causes unpredictable result such as accessing io port.
> + * So clear the hotplug flag to work around it.
> + */
> +static void quirk_apple_mbp_poweroff(struct pci_dev *dev)
> +{
> +	if (dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,4") ||
> +	    dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,5"))
> +		dev->is_hotplug_bridge = 0;
> +}
> +
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x8c10, quirk_apple_mbp_poweroff);
> +
> +/*
>   * This is a quirk for the Ricoh MMC controller found as a part of

I give up.  We're not making any progress on this.  I propose the
following patch for v4.13.  This is slightly modified to:

  - move to arch/x86/pci/fixups.c, since I think this is specific to
    x86

  - only clear dev->is_hotplug_bridge for the 00:1c.0 bridge, since
    these systems contain other bridges where I think we *do* want to
    support hotplug, e.g., the Thunderbolt bridge at 09:00.0 (from
    https://bugzilla.kernel.org/attachment.cgi?id=210611)

  - log a note in dmesg about what we're doing

commit f7bf6baa11b84534d0b7f5ceee06e3349948c853
Author: Chen Yu <yu.c.chen@xxxxxxxxx>
Date:   Fri Aug 19 16:30:25 2016 +0800

    PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11
    
    Neither soft poweroff (transition to ACPI power state S5) nor
    suspend-to-RAM (transition to state S3) works on the Macbook Pro 11,4 and
    11,5.
    
    The problem is related to assigning the [mem 0x7fa00000-0x7fbfffff] space
    to the 00:1c.0 Root Port.  This port isn't connected to anything, but it
    advertises hotplug support in its PCIe Capability.  Initially it has no
    windows assigned, and if Linux leaves it that way, poweroff and
    suspend-to-RAM work fine.
    
    Since the port supports hotplug, Linux assigns windows for future hot-added
    devices.  We currently assign [mem 0x7fa00000-0x7fbfffff] for the memory
    window, and poweroff and suspend-to-RAM don't work after this assignment.
    
    Linux does a soft poweroff (transition to S5) by writing to PM1_CNT at
    [io 0x1804].  The theory about why this doesn't work is:
    
      - The write to PM1_CNT causes an SMI.
      - The BIOS SMI handler depends on something in [mem 0x7fa00000-0x7fbfffff].
      - When Linux assigns [mem 0x7fa00000-0x7fbfffff] to the 00:1c.0 Port, it
        covers up whatever the SMI handler uses, so the SMI handler no longer
        works correctly.
    
    Mark the 00:1c.0 bridge as not supporting hotplug, so we don't assign the
    [mem 0x7fa00000-0x7fbfffff] space to it.
    
    Note that we don't know what the real conflict is, so other use of this
    memory range by another device may cause similar problems.
    
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=103211
    Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
    [bhelgaas: limit to device 00:1c.0, add printk, changelog, comment]
    Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
    Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
    Cc: Lukas Wunner <lukas@xxxxxxxxx>

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index 6d52b94f4bb9..e6b3bf9ecf81 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -571,3 +571,29 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2fc0, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6f60, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fa0, pci_invalid_bar);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x6fc0, pci_invalid_bar);
+
+/*
+ * Apple: Avoid programming the memory/io apertures of 00:1c.0
+ *
+ * The BIOS does not assign any windows to the 00:1c.0 Root Port, but the
+ * port advertises hotplug support in the PCIe Capability, so Linux assigns
+ *
+ *   [mem 0x7fa00000 - 0x7fbfffff]
+ *
+ * This assignment somehow causes a conflict with I/O port 0x1804, which is
+ * used for soft poweroff and suspend-to-RAM.  Clear the hotplug flag to
+ * keep Linux from assigning the window above.
+ *
+ * N.B. We don't know what the conflict is, so other use of this memory
+ * range by another device may cause similar problems.
+ */
+static void quirk_apple_mbp_poweroff(struct pci_dev *dev)
+{
+	if ((dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,4") ||
+	     dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,5")) &&
+	    dev->bus->number == 0 && dev->devfn == PCI_DEVFN(0x1c, 0)) {
+		dev_info(&dev->dev, "treating as non-hotplug bridge to work around poweroff issue\n");
+		dev->is_hotplug_bridge = 0;
+	}
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x8c10, quirk_apple_mbp_poweroff);