linux-kernel - x86/pci/mrst: force all pci config toward 0:0:0, 0:2:0 and 0:3:0 to type 1

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Message-ID: <20130430072147.GA37866@bingao-desk1.fm.intel.com>
Date:	Tue, 30 Apr 2013 00:21:47 -0700
From:	Bin Gao <bin.gao@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: x86/pci/mrst: force all pci config toward 0:0:0, 0:2:0 and 0:3:0 to
 type 1

x86/pci/mrst: force all pci config access toward 0:0:0, 0:2:0 and 0:3:0 to type 1

For real pci devices 0:0:0, 0:2:0 and 0:3:0, there is either no pci shim, or
no guarantee of data correctness of offset 256-4k. So for whatever reason,
Linux kernel should not do MMCFG pci config access to those devices. Instead,
always use type 1 for those devices.

Signed-off-by: Bin Gao <bin.gao@...ux.intel.com>
---
 arch/x86/pci/mrst.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c
index 6eb18c4..0e0fabf 100644
--- a/arch/x86/pci/mrst.c
+++ b/arch/x86/pci/mrst.c
@@ -141,6 +141,11 @@ static int pci_device_update_fixed(struct pci_bus *bus, unsigned int devfn,
  */
 static bool type1_access_ok(unsigned int bus, unsigned int devfn, int reg)
 {
+	if (bus == 0 && (devfn == PCI_DEVFN(2, 0)
+				|| devfn == PCI_DEVFN(0, 0)
+				|| devfn == PCI_DEVFN(3, 0)))
+		return 1;
+
 	/* This is a workaround for A0 LNC bug where PCI status register does
 	 * not have new CAP bit set. can not be written by SW either.
 	 *
@@ -150,10 +155,7 @@ static bool type1_access_ok(unsigned int bus, unsigned int devfn, int reg)
 	 */
 	if (reg >= 0x100 || reg == PCI_STATUS || reg == PCI_HEADER_TYPE)
 		return 0;
-	if (bus == 0 && (devfn == PCI_DEVFN(2, 0)
-				|| devfn == PCI_DEVFN(0, 0)
-				|| devfn == PCI_DEVFN(3, 0)))
-		return 1;
+
 	return 0; /* langwell on others */
 }
 
-- 
1.7.4.4

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