[Xen-devel] [LINUX] dma: Use swiotlb mask for coherent mappings too

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Hi Keir:

[LINUX] dma: Use swiotlb mask for coherent mappings too

The recent change to use a default DMA bit width of 30 bits (required
by chips like the b44) only converted the streaming DMA primitives.
The coherent mappings are still hard-coded to 31 bits.  This means that
b44 still doesn't work under Xen.

This patch makes the io_tlb_dma_bits variable global and uses it for
coherent memory mappings.

Thanks to Calvin Webster for providing a machine with a b44 and 2G
of memory I've been able to verify that this finally makes the b44
work under Xen.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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diff -r 057f7c4dbed1 linux-2.6-xen-sparse/arch/i386/kernel/pci-dma-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/kernel/pci-dma-xen.c       Tue Dec 19 
12:00:11 2006 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/kernel/pci-dma-xen.c       Wed Dec 20 
16:07:24 2006 +1100
@@ -15,6 +15,7 @@
 #include <linux/version.h>
 #include <asm/io.h>
 #include <xen/balloon.h>
+#include <asm/swiotlb.h>
 #include <asm/tlbflush.h>
 #include <asm-i386/mach-xen/asm/swiotlb.h>
 #include <asm/bug.h>
@@ -183,8 +184,8 @@ void *dma_alloc_coherent(struct device *
        ret = (void *)vstart;
 
        if (ret != NULL) {
-               /* NB. Hardcode 31 address bits for now: aacraid limitation. */
-               if (xen_create_contiguous_region(vstart, order, 31) != 0) {
+               if (xen_create_contiguous_region(vstart, order,
+                                                io_tlb_dma_bits) != 0) {
                        free_pages(vstart, order);
                        return NULL;
                }
diff -r 057f7c4dbed1 linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c
--- a/linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c   Tue Dec 19 12:00:11 
2006 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/kernel/swiotlb.c   Wed Dec 20 16:07:24 
2006 +1100
@@ -98,7 +98,7 @@ static struct phys_addr {
  */
 static DEFINE_SPINLOCK(io_tlb_lock);
 
-static unsigned int io_tlb_dma_bits = DEFAULT_IO_TLB_DMA_BITS;
+unsigned int io_tlb_dma_bits = DEFAULT_IO_TLB_DMA_BITS;
 static int __init
 setup_io_tlb_bits(char *str)
 {
diff -r 057f7c4dbed1 
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/swiotlb.h
--- a/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/swiotlb.h      Tue Dec 
19 12:00:11 2006 +0000
+++ b/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/swiotlb.h      Wed Dec 
20 16:07:24 2006 +1100
@@ -34,6 +34,8 @@ extern int swiotlb_dma_supported(struct 
 extern int swiotlb_dma_supported(struct device *hwdev, u64 mask);
 extern void swiotlb_init(void);
 
+extern int io_tlb_dma_bits;
+
 #ifdef CONFIG_SWIOTLB
 extern int swiotlb;
 #else

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