From: Tejun Heo <tj@kernel.org>
Date: Mon, 26 Oct 2009 14:41:46 +0000 (+0100)
Subject: x86: Fix iommu=nodac parameter handling
X-Git-Tag: firefly_0821_release~11625^2~616
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=704c528bee45fc37546542bf578181cec0845a67;p=firefly-linux-kernel-4.4.55.git

x86: Fix iommu=nodac parameter handling

commit 2ae8bb75db1f3de422eb5898f2a063c46c36dba8 upstream.

iommu=nodac should forbid dac instead of enabling it. Fix it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Matteo Frigo <athena@fftw.org>
LKML-Reference: <4AE5B52A.4050408@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index a6e804d16c35..6ac3931160d7 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -214,7 +214,7 @@ static __init int iommu_setup(char *p)
 		if (!strncmp(p, "allowdac", 8))
 			forbid_dac = 0;
 		if (!strncmp(p, "nodac", 5))
-			forbid_dac = -1;
+			forbid_dac = 1;
 		if (!strncmp(p, "usedac", 6)) {
 			forbid_dac = -1;
 			return 1;