linux-kernel - [PATCH 2/4] x86/PCI: Mark HPET BAR as IORESOURCE_PCI

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Date:	Fri, 25 Apr 2014 11:16:39 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	linux-pci@...r.kernel.org
Cc:	David Airlie <airlied@...ux.ie>, Bodo Eggert <7eggert@....de>,
	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] x86/PCI: Mark HPET BAR as IORESOURCE_PCI_FIXED

Bodo reported that on the Asrock M3A UCC, v3.12.6 hangs during boot unless
he uses "pci=nocrs".  This regression was caused by 7bc5e3f2be32 ("x86/PCI:
use host bridge _CRS info by default on 2008 and newer machines"), which
appeared in v2.6.34.

The reason is that the HPET address appears in a PCI device BAR, and this
address is not contained in any of the host bridge windows.  Linux moves
the PCI BAR into a window, but the original address was published via the
HPET table and an ACPI device, so changing the BAR is a bad idea:

  ACPI: HPET id: 0x43538301 base: 0xfed00000
  pci_root PNP0A03:00: host bridge window [mem 0xd0000000-0xdfffffff]
  pci_root PNP0A03:00: host bridge window [mem 0xf0000000-0xfebfffff]
  pci 0000:00:14.0: [1002:4385] type 0 class 0x000c05
  pci 0000:00:14.0: reg 14: [mem 0xfed00000-0xfed003ff]
  hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
  pnp 00:06: Plug and Play ACPI device, IDs PNP0103 (active)
  pnp 00:06: [mem 0xfed00000-0xfed003ff]

This patch marks the BAR as IORESOURCE_PCI_FIXED to prevent Linux from
moving it.  This depends on a previous patch ("x86/PCI: Don't try to move
IORESOURCE_PCI_FIXED resources") to check for this flag when
pci_claim_resource() fails.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=68591
Reported-by: Bodo Eggert <7eggert@....de>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 arch/x86/pci/fixup.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index 94ae9ae9574f..d4359f9d74b6 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -6,6 +6,7 @@
 #include <linux/dmi.h>
 #include <linux/pci.h>
 #include <linux/vgaarb.h>
+#include <asm/hpet.h>
 #include <asm/pci_x86.h>
 
 static void pci_fixup_i450nx(struct pci_dev *d)
@@ -526,6 +527,17 @@ static void sb600_disable_hpet_bar(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_ATI, 0x4385, sb600_disable_hpet_bar);
 
+static void sb600_hpet_quirk(struct pci_dev *dev)
+{
+	struct resource *r = &dev->resource[0];
+
+	if (r->flags & IORESOURCE_MEM && r->start == hpet_address) {
+		r->flags |= IORESOURCE_PCI_FIXED;
+		dev_info(&dev->dev, "reg 0x10 contains HPET; making it immovable\n");
+	}
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATI, 0x4385, sb600_hpet_quirk);
+
 /*
  * Twinhead H12Y needs us to block out a region otherwise we map devices
  * there and any access kills the box.

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