diff --git a/arch/powerpc/platforms/44x/currituck.c b/arch/powerpc/platforms/44x/currituck.c
index 583e67fee37ee1fd4daddc84ea3064fc4178ed6c..9f6c33d63a42c207a80444650646c1b3a1af7d08 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 dd3617c531d74260e01cbd88640e586a9f9ea2bd..925b02874233fe52dc118eec691a334d3be5fde8 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 18014629416df50976ccc74e93fcb99cccc6f7ce..b6a728b0a8ca0aae6427e619046633b94a35cd25 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 585bd22b14062b897bc18d0be1244f8e52cc4030..767c7cf18a9c978f7b9b70f700ed5ca496fdfd73 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 1fd91e9e0ffbc766452a925edd6eb8007b56a422..d30f6c47917d968ca72e088fae7bccf0b7207356 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 d208ebccb91cc5f5db92bee1cf47e82e0e0c4b31..8e4b094c553b49d142bceba1f29cf48c0805ed18 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 f700c81a1321ca2de222b6f1561408e454094204..74e310b4b460b3ddba96b336014bb74e1b642591 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 3755e61d7ecfac489a8ca6837a93f49c54132782..817245bc02195a37917b5dd341d7790ba5a50737 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;