linux-kernel - Re: [PATCH v10 06/59] PCI: Kill wrong quirk about M7101

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Message-ID: <CAE9FiQVAPfb-PYGQoRJzXdn3NAOK-X25M9pWvR2m7_9qT5qQ+w@mail.gmail.com>
Date:	Fri, 11 Mar 2016 14:08:11 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <helgaas@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	David Miller <davem@...emloft.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>, TJ <linux@....tj>,
	Yijing Wang <wangyijing@...wei.com>,
	Khalid Aziz <khalid.aziz@...cle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Meelis Roos <mroos@...ux.ee>
Subject: Re: [PATCH v10 06/59] PCI: Kill wrong quirk about M7101

On Thu, Mar 10, 2016 at 9:40 AM, Bjorn Helgaas <helgaas@...nel.org> wrote:
> On Wed, Feb 24, 2016 at 06:11:57PM -0800, Yinghai Lu wrote:
>> Meelis reported that qla2000 driver does not get loaded on one sparc system.
>>
>> schizo f00732d0: PCI host bridge to bus 0001:00
>> pci_bus 0001:00: root bus resource [io  0x7fe01000000-0x7fe01ffffff] (bus address [0x0000-0xffffff])
>> pci 0001:00:06.0: quirk: [io  0x7fe01000800-0x7fe0100083f] claimed by ali7101 ACPI
>> pci 0001:00:06.0: quirk: [io  0x7fe01000600-0x7fe0100061f] claimed by ali7101 SMB
>> pci 0001:00:07.0: can't claim BAR 0 [io  0x7fe01000000-0x7fe0100ffff]: address conflict with 0001:00:06.0 [io  0x7fe01000600-0x7fe0100061f]
>>
>> So the quirk for M7101 claim the io range early.
>>
>> According to spec with M7101 in M1543 page 103/104,
>>       http://www.versalogic.com/Support/Downloads/pdf/ali1543.pdf
>> 0xe0, and 0xe2 do not include address info for acpi/smb.
>>
>> Kill wrong quirk about them.
>
> This needs an explanation for why the quirk was added in the first
> place, and why it is now safe to remove it.

The related commit does not tell much about why it is there exactly.
But it is added the same time with intel piix4.

Maybe Linus could have some hint about that quirk?

commit 34f550135e349102bd065488eabbbb217ab27f0d
Author: Linus Torvalds <torvalds@...uxfoundation.org>
Date:   Fri Nov 23 15:32:20 2007 -0500

    Import 2.3.49pre2

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index cda39a5..8029b19 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -113,6 +113,55 @@ static void __init quirk_s3_64M(struct pci_dev *dev)
        }
 }

+static void __init quirk_io_region(struct pci_dev *dev, unsigned region, unsign
ed size, int nr)
+{
+       region &= ~(size-1);
+       if (region) {
+               struct resource *res = dev->resource + nr;
+
+               res->name = dev->name;
+               res->start = region;
+               res->end = region + size - 1;
+               res->flags = IORESOURCE_IO;
+               pci_claim_resource(dev, nr);
+       }
+}
+
+/*
+ * Let's make the southbridge information explicit instead
+ * of having to worry about people probing the ACPI areas,
+ * for example.. (Yes, it happens, and if you read the wrong
+ * ACPI register it will put the machine to sleep with no
+ * way of waking it up again. Bummer).
+ *
+ * ALI M7101: Two IO regions pointed to by words at
+ *     0xE0 (64 bytes of ACPI registers)
+ *     0xE2 (32 bytes of SMB registers)
+ */
+static void __init quirk_ali7101(struct pci_dev *dev)
+{
+       u16 region;
+
+       pci_read_config_word(dev, 0xE0, &region);
+       quirk_io_region(dev, region, 64, PCI_BRIDGE_RESOURCES);
+       pci_read_config_word(dev, 0xE2, &region);
+       quirk_io_region(dev, region, 32, PCI_BRIDGE_RESOURCES+1);
+}
+
+/*
+ * PIIX4 ACPI: Two IO regions pointed to by longwords at
+ *     0x40 (64 bytes of ACPI registers)
+ *     0x90 (32 bytes of SMB registers)
+ */
+static void __init quirk_piix4acpi(struct pci_dev *dev)
+{
+       u32 region;
+
+       pci_read_config_dword(dev, 0x40, &region);
+       quirk_io_region(dev, region, 64, PCI_BRIDGE_RESOURCES);
+       pci_read_config_dword(dev, 0x90, &region);
+       quirk_io_region(dev, region, 32, PCI_BRIDGE_RESOURCES+1);
+}

 /*
  *  The main table of quirks.
@@ -143,6 +192,8 @@ static struct pci_fixup pci_fixups[] __initdata = {
        { PCI_FIXUP_FINAL,      PCI_VENDOR_ID_INTEL,
PCI_DEVICE_ID_INTEL_82443BX_2,  quirk_natoma },
        { PCI_FIXUP_FINAL,      PCI_VENDOR_ID_SI,
PCI_DEVICE_ID_SI_5597,          quirk_nopcipci },
        { PCI_FIXUP_FINAL,      PCI_VENDOR_ID_SI,
PCI_DEVICE_ID_SI_496,           quirk_nopcipci },
+       { PCI_FIXUP_FINAL,      PCI_VENDOR_ID_INTEL,
PCI_DEVICE_ID_INTEL_82371AB_3,  quirk_piix4acpi },
+       { PCI_FIXUP_FINAL,      PCI_VENDOR_ID_AL,
PCI_DEVICE_ID_AL_M7101,         quirk_ali7101 },
        { 0 }
 };