From: Glauber Costa <gcosta@redhat.com>
Date: Tue, 8 Apr 2008 16:21:04 +0000 (-0300)
Subject: x86: use a fallback dev for i386
X-Git-Tag: v2.6.26-rc1~1133^2~8
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=45a07e774950ef479f8996c0e2c5550dd6440453;p=linux-2.6-omap-h63xx.git

x86: use a fallback dev for i386

We can use a fallback dev for cases of a NULL device being passed (mostly ISA)
This comes from x86_64 implementation.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/arch/x86/kernel/pci-dma_32.c b/arch/x86/kernel/pci-dma_32.c
index 0d630ae3d91..0600a37ba83 100644
--- a/arch/x86/kernel/pci-dma_32.c
+++ b/arch/x86/kernel/pci-dma_32.c
@@ -14,6 +14,16 @@
 #include <linux/module.h>
 #include <asm/io.h>
 
+/* Dummy device used for NULL arguments (normally ISA). Better would
+   be probably a smaller DMA mask, but this is bug-to-bug compatible
+   to i386. */
+struct device fallback_dev = {
+	.bus_id = "fallback device",
+	.coherent_dma_mask = DMA_32BIT_MASK,
+	.dma_mask = &fallback_dev.coherent_dma_mask,
+};
+
+
 static int dma_alloc_from_coherent_mem(struct device *dev, ssize_t size,
 				       dma_addr_t *dma_handle, void **ret)
 {
@@ -75,6 +85,9 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
 	if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
 		gfp |= GFP_DMA;
 
+	if (!dev)
+		dev = &fallback_dev;
+
 	page = dma_alloc_pages(dev, gfp, order);
 	if (page == NULL)
 		return NULL;