diff --git a/arch/blackfin/mach-bf533/boards/stamp.c b/arch/blackfin/mach-bf533/boards/stamp.c
index f84be4eabfd1..62ffa500420f 100644
--- a/arch/blackfin/mach-bf533/boards/stamp.c
+++ b/arch/blackfin/mach-bf533/boards/stamp.c
@@ -218,7 +218,7 @@ static struct spi_board_info bfin_spi_board_info[] __initdata = {
 #if defined(CONFIG_SPI_MMC) || defined(CONFIG_SPI_MMC_MODULE)
 	{
 		.modalias = "spi_mmc_dummy",
-		.max_speed_hz = 25000000,     /* max spi clock (SCK) speed in HZ */
+		.max_speed_hz = 20000000,     /* max spi clock (SCK) speed in HZ */
 		.bus_num = 0,
 		.chip_select = 0,
 		.platform_data = NULL,
@@ -227,7 +227,7 @@ static struct spi_board_info bfin_spi_board_info[] __initdata = {
 	},
 	{
 		.modalias = "spi_mmc",
-		.max_speed_hz = 25000000,     /* max spi clock (SCK) speed in HZ */
+		.max_speed_hz = 20000000,     /* max spi clock (SCK) speed in HZ */
 		.bus_num = 0,
 		.chip_select = CONFIG_SPI_MMC_CS_CHAN,
 		.platform_data = NULL,
diff --git a/arch/blackfin/mach-bf537/boards/stamp.c b/arch/blackfin/mach-bf537/boards/stamp.c
index cc41f6c2ef4f..c18d85e8a0b6 100644
--- a/arch/blackfin/mach-bf537/boards/stamp.c
+++ b/arch/blackfin/mach-bf537/boards/stamp.c
@@ -450,7 +450,7 @@ static struct spi_board_info bfin_spi_board_info[] __initdata = {
 #if defined(CONFIG_SPI_MMC) || defined(CONFIG_SPI_MMC_MODULE)
 	{
 		.modalias = "spi_mmc_dummy",
-		.max_speed_hz = 25000000,     /* max spi clock (SCK) speed in HZ */
+		.max_speed_hz = 20000000,     /* max spi clock (SCK) speed in HZ */
 		.bus_num = 0,
 		.chip_select = 0,
 		.platform_data = NULL,
@@ -459,7 +459,7 @@ static struct spi_board_info bfin_spi_board_info[] __initdata = {
 	},
 	{
 		.modalias = "spi_mmc",
-		.max_speed_hz = 25000000,     /* max spi clock (SCK) speed in HZ */
+		.max_speed_hz = 20000000,     /* max spi clock (SCK) speed in HZ */
 		.bus_num = 0,
 		.chip_select = CONFIG_SPI_MMC_CS_CHAN,
 		.platform_data = NULL,