diff --git a/arch/powerpc/boot/dts/p1010rdb.dtsi b/arch/powerpc/boot/dts/p1010rdb.dtsi
index d4c4a7730285501317523ab39054825ff3d2df7a..1c41ef0c817cb670f48804d2efd5549a6a406691 100644
--- a/arch/powerpc/boot/dts/p1010rdb.dtsi
+++ b/arch/powerpc/boot/dts/p1010rdb.dtsi
@@ -138,7 +138,7 @@
 			#size-cells = <1>;
 			compatible = "spansion,s25sl12801";
 			reg = <0>;
-			spi-max-frequency = <50000000>;
+			spi-max-frequency = <40000000>;
 
 			partition@0 {
 				/* 1MB for u-boot Bootloader Image */
diff --git a/arch/powerpc/boot/dts/p2020rdb.dts b/arch/powerpc/boot/dts/p2020rdb.dts
index 8f25ef2e6e429932b66eaad065715c2268d9c7ed..153bc76bb48ea75cc93ca9d93d41207fe420a147 100644
--- a/arch/powerpc/boot/dts/p2020rdb.dts
+++ b/arch/powerpc/boot/dts/p2020rdb.dts
@@ -157,7 +157,7 @@
 				#size-cells = <1>;
 				compatible = "spansion,s25sl12801";
 				reg = <0>;
-				spi-max-frequency = <50000000>;
+				spi-max-frequency = <40000000>;
 
 				partition@0 {
 					/* 512KB for u-boot Bootloader Image */