After we set the GET_TIME bit, the rtc time couldn't be read immediately,
we should wait up to 31.25 us, about one cycle of 32khz. Otherwise reading
RTC time will return a old time. If clear the GET_TIME bit after setting,
the time of i2c transfer certainly more than 31.25us.
Signed-off-by: Chris Zhong <zyw at rock-chips.com>
---
drivers/rtc/rtc-rk808.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/rtc/rtc-rk808.c b/drivers/rtc/rtc-rk808.c
index df42257..8dae322 100644
--- a/drivers/rtc/rtc-rk808.c
+++ b/drivers/rtc/rtc-rk808.c
@@ -67,15 +67,20 @@ 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 couldn't be read
+ * immediately, 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.
+ */
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;
--
1.9.1
