1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/rtc/rtc-rk808.c b/drivers/rtc/rtc-rk808.c
index df42257668ac..91ca0bc1b484 100644
--- a/drivers/rtc/rtc-rk808.c
+++ b/drivers/rtc/rtc-rk808.c
@@ -67,15 +67,21 @@ static int rk808_rtc_readtime(struct device *dev, struct rtc_time *tm)
         /* Force an update of the shadowed registers right now */
         ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
                                  BIT_RTC_CTRL_REG_RTC_GET_TIME,
-                                 0);
+                                 BIT_RTC_CTRL_REG_RTC_GET_TIME);
         if (ret) {
                 dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
                 return ret;
         }
 
+        /*
+         * After we set the GET_TIME bit, the rtc time can't be read
+         * immediately. So we should wait up to 31.25 us, about one cycle of
+         * 32khz. If we clear the GET_TIME bit here, the time of i2c transfer
+         * certainly more than 31.25us: 16 * 2.5us at 400kHz bus frequency.
+         */
         ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
                                  BIT_RTC_CTRL_REG_RTC_GET_TIME,
-                                 BIT_RTC_CTRL_REG_RTC_GET_TIME);
+                                 0);
         if (ret) {
                 dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
                 return ret;