From dfdbf3f6e2d279f2a46ed95614cb4bf07657394d Mon Sep 17 00:00:00 2001
From: Ian Wisbon <ian.wisbon@timesys.com>
Date: Tue, 15 Feb 2011 15:53:51 -0500
Subject: Digi del-5.6 Complete

---
 arch/x86/pci/i386.c | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'arch/x86/pci/i386.c')

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 52e62e57fedd..5da8792b48a4 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -282,6 +282,15 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 		return -EINVAL;
 
 	prot = pgprot_val(vma->vm_page_prot);
+
+	/*
+ 	 * Return error if pat is not enabled and write_combine is requested.
+ 	 * Caller can followup with UC MINUS request and add a WC mtrr if there
+ 	 * is a free mtrr slot.
+ 	 */
+	if (!pat_enabled && write_combine)
+		return -EINVAL;
+
 	if (pat_enabled && write_combine)
 		prot |= _PAGE_CACHE_WC;
 	else if (pat_enabled || boot_cpu_data.x86 > 3)
-- 
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