Patch "PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pci-work-around-poweroff-suspend-to-ram-issue-on-macbook-pro-11.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bjorn Helgaas <[email protected]>
Date: Fri, 19 Aug 2016 16:30:25 +0800
Subject: PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11

From: Bjorn Helgaas <[email protected]>

commit 13cfc732160f7bc7e596128ce34cda361c556966 upstream.

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 the [mem 0x7fa00000-0x7fbfffff] space. When we use that space, e.g., by assigning it to the 00:1c.0 Root Port, the ACPI Power Management 1 Control Register (PM1_CNT) at [io 0x1804] doesn't work anymore.

Linux does a soft poweroff (transition to S5) by writing to PM1_CNT. 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

Reserve the [mem 0x7fa00000-0x7fbfffff] space so we don't assign it to anything.

This is voodoo programming, since we don't know what the real conflict is, but we've failed to find the root cause.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=103211

---
 arch/x86/pci/fixup.c |   32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

@@ -571,3 +571,35 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_IN
 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 MacBook Pro: Avoid [mem 0x7fa00000-0x7fbfffff]
+ *
+ * Using the [mem 0x7fa00000-0x7fbfffff] region, e.g., by assigning it to
+ * the 00:1c.0 Root Port, causes a conflict with [io 0x1804], which is used
+ * for soft poweroff and suspend-to-RAM.
+ *
+ * As far as we know, this is related to the address space, not to the Root
+ * Port itself.  Attaching the quirk to the Root Port is a convenience, but
+ * it could probably also be a standalone DMI quirk.
+ *
+ * https://bugzilla.kernel.org/show_bug.cgi?id=103211
+ */
+static void quirk_apple_mbp_poweroff(struct pci_dev *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+
+	if ((!dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,4") &&
+	     !dmi_match(DMI_PRODUCT_NAME, "MacBookPro11,5")) ||
+	    pdev->bus->number != 0 || pdev->devfn != PCI_DEVFN(0x1c, 0))
+		return;
+
+	res = request_mem_region(0x7fa00000, 0x200000,
+				 "MacBook Pro poweroff workaround");
+	if (res)
+		dev_info(dev, "claimed %s %pR\n", res->name, res);
+	else
+		dev_info(dev, "can't work around MacBook Pro poweroff issue\n");
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x8c10, quirk_apple_mbp_poweroff);

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/pci-msi-ignore-affinity-if-pre-post-vector-count-is-more-than-min_vecs.patch queue-4.12/pci-work-around-poweroff-suspend-to-ram-issue-on-macbook-pro-11.patch queue-4.12/pci-rockchip-use-normal-register-bank-for-config-accessors.patch queue-4.12/pci-vmd-move-srcu-cleanup-after-bus-child-device-removal.patch queue-4.12/pci-pm-restore-the-status-of-pci-devices-across-hibernation.patch