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-rw-r--r--drivers/rtc/interface.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 9eb32ead63db..672b192f8153 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -1004,6 +1004,10 @@ int rtc_read_offset(struct rtc_device *rtc, long *offset)
* to compensate for differences in the actual clock rate due to temperature,
* the crystal, capacitor, etc.
*
+ * The adjustment applied is as follows:
+ * t = t0 * (1 + offset * 1e-9)
+ * where t0 is the measured length of 1 RTC second with offset = 0
+ *
* Kernel interface to adjust an rtc clock offset.
* Return 0 on success, or a negative number on error.
* If the rtc offset is not setable (or not implemented), return -EINVAL