2 files changed, 17 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-s5m.c b/drivers/rtc/rtc-s5m.c
index 22137d4dbadf..3751ef90f93c 100644
--- a/drivers/rtc/rtc-s5m.c
+++ b/drivers/rtc/rtc-s5m.c
@@ -519,6 +519,13 @@ static int s5m8767_rtc_init_reg(struct s5m_rtc_info *info)
         u8 data[2];
         int ret;
 
+        /* UDR update time. Default of 7.32 ms is too long. */
+        ret = regmap_update_bits(info->regmap, S5M_RTC_UDR_CON,
+                        S5M_RTC_UDR_T_MASK, S5M_RTC_UDR_T_450_US);
+        if (ret < 0)
+                dev_err(info->dev, "%s: fail to change UDR time: %d\n",
+                                __func__, ret);
+
         /* Set RTC control register : Binary mode, 24hour mode */
         data[0] = (1 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
         data[1] = (0 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
diff --git a/include/linux/mfd/samsung/rtc.h b/include/linux/mfd/samsung/rtc.h
index 207fcfbde82e..b6401e7661c7 100644
--- a/include/linux/mfd/samsung/rtc.h
+++ b/include/linux/mfd/samsung/rtc.h
@@ -111,6 +111,16 @@ enum s2mps_rtc_reg {
 #define RTC_TCON_MASK           (1 << RTC_TCON_SHIFT)
 #define S5M_RTC_TIME_EN_SHIFT   3
 #define S5M_RTC_TIME_EN_MASK    (1 << S5M_RTC_TIME_EN_SHIFT)
+/*
+ * UDR_T field in S5M_RTC_UDR_CON register determines the time needed
+ * for updating alarm and time registers. Default is 7.32 ms.
+ */
+#define S5M_RTC_UDR_T_SHIFT     6
+#define S5M_RTC_UDR_T_MASK      (0x3 << S5M_RTC_UDR_T_SHIFT)
+#define S5M_RTC_UDR_T_7320_US   (0x0 << S5M_RTC_UDR_T_SHIFT)
+#define S5M_RTC_UDR_T_1830_US   (0x1 << S5M_RTC_UDR_T_SHIFT)
+#define S5M_RTC_UDR_T_3660_US   (0x2 << S5M_RTC_UDR_T_SHIFT)
+#define S5M_RTC_UDR_T_450_US    (0x3 << S5M_RTC_UDR_T_SHIFT)
 
 /* RTC Hour register */
 #define HOUR_PM_SHIFT           6