diff options
| -rw-r--r-- | drivers/rtc/rtc-rk808.c | 10 |
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; |