diff --git a/configs/firefly-rk3399_defconfig b/configs/firefly-rk3399_defconfig
index 3b3be22..6725b48 100644
--- a/configs/firefly-rk3399_defconfig
+++ b/configs/firefly-rk3399_defconfig
@@ -44,6 +44,7 @@
 CONFIG_MMC_DW_ROCKCHIP=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ROCKCHIP=y
+CONFIG_SF_DEFAULT_SPEED=20000000
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_GMAC_ROCKCHIP=y