From c31e74c4c34fa863393c28b95409aee934b4f8e1 Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Tue, 10 Aug 2010 18:03:25 -0700
Subject: [PATCH] Documentation: DMA-API-HOWTO.txt: add multiple types of
 IOMMUs support

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Documentation/DMA-API-HOWTO.txt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 98ce51796f711..3c4e07123e59a 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -753,6 +753,16 @@ to "Closing".
    alignment constraints (e.g. the alignment constraints about 64-bit
    objects).
 
+3) Supporting multiple types of IOMMUs
+
+   If your architecture needs to support multiple types of IOMMUs, you
+   can use include/linux/asm-generic/dma-mapping-common.h. It's a
+   library to support the DMA API with multiple types of IOMMUs. Lots
+   of architectures (x86, powerpc, sh, alpha, ia64, microblaze and
+   sparc) use it. Choose one to see how it can be used. If you need to
+   support multiple types of IOMMUs in a single system, the example of
+   x86 or powerpc helps.
+
 			   Closing
 
 This document, and the API itself, would not be in its current
-- 
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