diff --git a/drivers/mmc/rockchip_sdhci.c b/drivers/mmc/rockchip_sdhci.c
index 761e3619329..5e025d76a82 100644
--- a/drivers/mmc/rockchip_sdhci.c
+++ b/drivers/mmc/rockchip_sdhci.c
@@ -500,7 +500,7 @@ static int rockchip_sdhci_execute_tuning(struct mmc *mmc, u8 opcode)
 {
 	struct rockchip_sdhc *priv = dev_get_priv(mmc->dev);
 	struct sdhci_host *host = &priv->host;
-	char tuning_loop_counter = SDHCI_TUNING_LOOP_COUNT;
+	s8 tuning_loop_counter = SDHCI_TUNING_LOOP_COUNT;
 	struct mmc_cmd cmd;
 	u32 ctrl, blk_size;
 	int ret;