ia64: Get rid of pci_dma_bus_is_phys in favor of ia64_max_iommu_merge_mask.

arch/ia64/hp/common/sba_iommu.c

@@ -1682,6 +1682,10 @@ ioc_init(u64 hpa, void *handle)
 	ioc_resource_init(ioc);
 	ioc_sac_init(ioc);
 
+	if ((long) ~IOVP_MASK > (long) ia64_max_iommu_merge_mask)
+		ia64_max_iommu_merge_mask = ~IOVP_MASK;
+	MAX_DMA_ADDRESS = ~0UL;
+
 	printk(KERN_INFO PFX
 		"%s %d.%d HPA 0x%lx IOVA space %dMb at 0x%lx\n",
 		ioc->name, (ioc->rev >> 4) & 0xF, ioc->rev & 0xF,
@@ -1933,9 +1937,6 @@ static struct acpi_driver acpi_sba_ioc_driver = {
 static int __init
 sba_init(void)
 {
-	pci_dma_bus_is_phys = 0;	/* suppress bounce buffer in block/net layers */
-	MAX_DMA_ADDRESS = ~0UL;
-
 	acpi_bus_register_driver(&acpi_sba_ioc_driver);
 
 #ifdef CONFIG_PCI

arch/ia64/kernel/setup.c

@@ -68,7 +68,16 @@ unsigned int num_io_spaces;
 unsigned char aux_device_present = 0xaa;        /* XXX remove this when legacy I/O is gone */
 
 #ifdef CONFIG_PCI
-int pci_dma_bus_is_phys = 1;	/* default to direct mapping, unless we detect hw I/O MMU */
+/*
+ * The merge_mask variable needs to be set to (max(iommu_page_size(iommu)) - 1).  This
+ * mask specifies a mask of address bits that must be 0 in order for two buffers to be
+ * mergeable by the I/O MMU (i.e., the end address of the first buffer and the start
+ * address of the second buffer must be aligned to (merge_mask+1) in order to be
+ * mergeable).  By default, we assume there is no I/O MMU which can merge physically
+ * discontiguous buffers, so we set the merge_mask to ~0UL, which corresponds to a iommu
+ * page-size of 2^64.
+ */
+unsigned long ia64_max_iommu_merge_mask = ~0UL;
 #endif
 
 #define COMMAND_LINE_SIZE	512

include/asm-ia64/io.h

@@ -413,8 +413,17 @@ extern void __ia64_memset_c_io (unsigned long, unsigned long, long);
 
 # endif /* __KERNEL__ */
 
-/* Argh, another magic macro... ;-( */
-extern int pci_dma_bus_is_phys;
-#define BIO_VMERGE_BOUNDARY	(pci_dma_bus_is_phys ? 0 : PAGE_SIZE)
+/*
+ * It makes no sense at all to have this BIO_VMERGE_BOUNDARY macro here.  Should be
+ * replaced by dma_merge_mask() or something of that sort.  Note: the only way
+ * BIO_VMERGE_BOUNDARY is used is to mask off bits.  Effectively, our definition gets
+ * expanded into:
+ *
+ *	addr & ((ia64_max_iommu_merge_mask + 1) - 1) == (addr & ia64_max_iommu_vmerge_mask)
+ *
+ * which is precisely what we want.
+ */
+extern unsigned long ia64_max_iommu_merge_mask;
+#define BIO_VMERGE_BOUNDARY	(ia64_max_iommu_merge_mask + 1)
 
 #endif /* _ASM_IA64_IO_H */