linux-kernel - Re: [PATCH] PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11

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Date:   Mon, 3 Jul 2017 14:33:39 +0800
From:   Ethan Zhao <ethan.kernel@...il.com>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, thejoe@...il.com,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH] PCI: Work around poweroff & suspend-to-RAM issue on
 Macbook Pro 11

On Mon, Jul 3, 2017 at 12:26 PM, Chen Yu <yu.c.chen@...el.com> wrote:
> Hi,
> On Sun, Jul 02, 2017 at 03:59:48PM -0500, Bjorn Helgaas wrote:
>> 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
>> Tested-by: thejoe@...il.com
>> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>> Cc: stable@...r.kernel.org
>> Cc: Rafael J. Wysocki <rafael@...nel.org>
>> Cc: Lukas Wunner <lukas@...ner.de>
>> Cc: Chen Yu <yu.c.chen@...el.com>
>>
>> diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
>> index 6d52b94f4bb9..20fa7c84109d 100644
>> --- a/arch/x86/pci/fixup.c
>> +++ b/arch/x86/pci/fixup.c
>> @@ -571,3 +571,35 @@ 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 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;
>> +
> Not sure why we need to also the bus number of devfn, as there
> is only one PCI bridge that would match 0x8c10? according to
> https://bugzilla.kernel.org/attachment.cgi?id=210611
> am I missing something?

 To make sure it runs only once only when 00:1c.0 is 0x8c10 ?

Thanks,
Ethan

> thanks,
> Yu
>> +     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);