x86, swiotlb: Simplify SWIOTLB pci_swiotlb_detect routine.

In 'pci_swiotlb_detect' we used to do two different things:
 a). If user provided 'iommu=soft' or 'swiotlb=force' we
     would set swiotlb=1 and return 1 (and forcing pci-dma.c
     to call pci_swiotlb_init() immediately).
 b). If 4GB or more would be detected and if user did not specify
     iommu=off, we would set 'swiotlb=1' and return whatever 'a)'
     figured out.

We simplify this by splitting a) and b) in two different routines.

CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <1282845485-8991-5-git-send-email-konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 9f07cfcbd3a5..1b3beb5075e6 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -133,9 +133,11 @@ void __init pci_iommu_alloc(void)
         /* free the range so iommu could get some range less than 4G */
         dma32_free_bootmem();
 
-        if (pci_xen_swiotlb_detect() || pci_swiotlb_detect())
+        if (pci_xen_swiotlb_detect() || pci_swiotlb_detect_override())
                 goto out;
 
+        pci_swiotlb_detect_4gb();
+
         gart_iommu_hole_init();
 
         detect_calgary();