File linux-2.6-omap3-iovmm-Work-around-sg_alloc_table-size-limitati.patch of Package kernel-adaptation-n900

From 066fdf53557c4d3b62c7ef66667cc1966e0cceeb Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Mon, 30 May 2011 14:47:08 +0200
Subject: [PATCH] omap3: iovmm: Work around sg_alloc_table size limitation in IOMMU

sg_alloc_table can only allocate multi-page scatter-gather list tables
if the architecture supports scatter-gather lists chaining. ARM doesn't
fit in that category.

The IOMMU driver abuses the sg table structure only to hold page
addresses without ever passing the table to the device.

Use __sg_alloc_table instead of sg_alloc_table and allocate all entries
in one go. This avoids hitting a BUG_ON in __sg_alloc_table while still
not faking sg list chaining support.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
---
 arch/arm/plat-omap/iovmm.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-omap/iovmm.c b/arch/arm/plat-omap/iovmm.c
index 51ef43e..b82cef4 100644
--- a/arch/arm/plat-omap/iovmm.c
+++ b/arch/arm/plat-omap/iovmm.c
@@ -121,6 +121,16 @@ static unsigned sgtable_nents(size_t bytes, u32 da, u32 pa)
 	return nr_entries;
 }
 
+static struct scatterlist *sg_alloc(unsigned int nents, gfp_t gfp_mask)
+{
+	return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
+}
+
+static void sg_free(struct scatterlist *sg, unsigned int nents)
+{
+	kfree(sg);
+}
+
 /* allocate and initialize sg_table header(a kind of 'superblock') */
 static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags,
 							u32 da, u32 pa)
@@ -146,7 +156,7 @@ static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags,
 	if (!sgt)
 		return ERR_PTR(-ENOMEM);
 
-	err = sg_alloc_table(sgt, nr_entries, GFP_KERNEL);
+	err = __sg_alloc_table(sgt, nr_entries, -1, GFP_KERNEL, sg_alloc);
 	if (err) {
 		kfree(sgt);
 		return ERR_PTR(err);
@@ -163,7 +173,7 @@ static void sgtable_free(struct sg_table *sgt)
 	if (!sgt)
 		return;
 
-	sg_free_table(sgt);
+	__sg_free_table(sgt, -1, sg_free);
 	kfree(sgt);
 
 	pr_debug("%s: sgt:%p\n", __func__, sgt);
-- 
1.7.0.4