diff --git a/arch/powerpc/platforms/44x/currituck.c b/arch/powerpc/platforms/44x/currituck.c
index 583e67f..9f6c33d 100644
--- a/arch/powerpc/platforms/44x/currituck.c
+++ b/arch/powerpc/platforms/44x/currituck.c
@@ -160,7 +160,7 @@ static void __init ppc47x_setup_arch(void)
 	/* No need to check the DMA config as we /know/ our windows are all of
  	 * RAM.  Lets hope that doesn't change */
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > 0xffffffff) {
+	if ((memblock_end_of_DRAM() - 1) > 0xffffffff) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/corenet_ds.c b/arch/powerpc/platforms/85xx/corenet_ds.c
index dd3617c..925b028 100644
--- a/arch/powerpc/platforms/85xx/corenet_ds.c
+++ b/arch/powerpc/platforms/85xx/corenet_ds.c
@@ -77,7 +77,7 @@ void __init corenet_ds_setup_arch(void)
 #endif
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/ge_imp3a.c b/arch/powerpc/platforms/85xx/ge_imp3a.c
index 1801462..b6a728b 100644
--- a/arch/powerpc/platforms/85xx/ge_imp3a.c
+++ b/arch/powerpc/platforms/85xx/ge_imp3a.c
@@ -125,7 +125,7 @@ static void __init ge_imp3a_setup_arch(void)
 	mpc85xx_smp_init();
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/mpc8536_ds.c b/arch/powerpc/platforms/85xx/mpc8536_ds.c
index 585bd22..767c7cf 100644
--- a/arch/powerpc/platforms/85xx/mpc8536_ds.c
+++ b/arch/powerpc/platforms/85xx/mpc8536_ds.c
@@ -75,7 +75,7 @@ static void __init mpc8536_ds_setup_arch(void)
 #endif
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/mpc85xx_ds.c b/arch/powerpc/platforms/85xx/mpc85xx_ds.c
index 1fd91e9..d30f6c4 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_ds.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_ds.c
@@ -173,7 +173,7 @@ static void __init mpc85xx_ds_setup_arch(void)
 	mpc85xx_smp_init();
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/mpc85xx_mds.c b/arch/powerpc/platforms/85xx/mpc85xx_mds.c
index d208ebc..8e4b094 100644
--- a/arch/powerpc/platforms/85xx/mpc85xx_mds.c
+++ b/arch/powerpc/platforms/85xx/mpc85xx_mds.c
@@ -359,7 +359,7 @@ static void __init mpc85xx_mds_setup_arch(void)
 	mpc85xx_mds_qe_init();
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/85xx/p1022_ds.c b/arch/powerpc/platforms/85xx/p1022_ds.c
index f700c81..74e310b 100644
--- a/arch/powerpc/platforms/85xx/p1022_ds.c
+++ b/arch/powerpc/platforms/85xx/p1022_ds.c
@@ -450,7 +450,7 @@ static void __init p1022_ds_setup_arch(void)
 	mpc85xx_smp_init();
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
diff --git a/arch/powerpc/platforms/86xx/mpc86xx_hpcn.c b/arch/powerpc/platforms/86xx/mpc86xx_hpcn.c
index 3755e61..817245b 100644
--- a/arch/powerpc/platforms/86xx/mpc86xx_hpcn.c
+++ b/arch/powerpc/platforms/86xx/mpc86xx_hpcn.c
@@ -102,7 +102,7 @@ mpc86xx_hpcn_setup_arch(void)
 #endif
 
 #ifdef CONFIG_SWIOTLB
-	if (memblock_end_of_DRAM() > max) {
+	if ((memblock_end_of_DRAM() - 1) > max) {
 		ppc_swiotlb_enable = 1;
 		set_pci_dma_ops(&swiotlb_dma_ops);
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_swiotlb;
