Hi Richard,

thank you for your comments.

Am Di., 30. Juli 2019 um 18:00 Uhr schrieb Richard Cochran
[off-list ref]:
[...]

quoted

-/* Raw timestamps are in units of 8-ns clock periods. */
-#define CC_SHIFT     28
-#define CC_MULT              (8 << CC_SHIFT)
-#define CC_MULT_NUM  (1 << 9)
-#define CC_MULT_DEM  15625ULL
+/* The adjfine API clamps ppb between [-32,768,000, 32,768,000], and

That is not true.

quoted

+ * therefore scaled_ppm between [-2,147,483,648, 2,147,483,647].
+ * Set the maximum supported ppb to a round value smaller than the maximum.
+ *
+ * Percentually speaking, this is a +/- 0.032x adjustment of the
+ * free-running counter (0.968x to 1.032x).
+ */
+#define MV88E6XXX_MAX_ADJ_PPB        32000000

I had set an arbitrary limit of 1000 ppm.  I can't really see any
point in raising the limit.

quoted

+/* Family MV88E6250:
+ * Raw timestamps are in units of 10-ns clock periods.
+ *
+ * clkadj = scaled_ppm * 10*2^28 / (10^6 * 2^16)
+ * simplifies to
+ * clkadj = scaled_ppm * 2^7 / 5^5
+ */
+#define MV88E6250_CC_SHIFT   28
+#define MV88E6250_CC_MULT    (10 << MV88E6250_CC_SHIFT)
+#define MV88E6250_CC_MULT_NUM        (1 << 7)
+#define MV88E6250_CC_MULT_DEM        3125ULL
+
+/* Other families:
+ * Raw timestamps are in units of 8-ns clock periods.
+ *
+ * clkadj = scaled_ppm * 8*2^28 / (10^6 * 2^16)
+ * simplifies to
+ * clkadj = scaled_ppm * 2^9 / 5^6
+ */
+#define MV88E6XXX_CC_SHIFT   28
+#define MV88E6XXX_CC_MULT    (8 << MV88E6XXX_CC_SHIFT)
+#define MV88E6XXX_CC_MULT_NUM        (1 << 9)
+#define MV88E6XXX_CC_MULT_DEM        15625ULL

 #define TAI_EVENT_WORK_INTERVAL msecs_to_jiffies(100)

@@ -179,24 +206,14 @@ static void mv88e6352_tai_event_work(struct work_struct *ugly)
 static int mv88e6xxx_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 {
      struct mv88e6xxx_chip *chip = ptp_to_chip(ptp);
-     int neg_adj = 0;
-     u32 diff, mult;
-     u64 adj;
+     s64 adj;

-     if (scaled_ppm < 0) {
-             neg_adj = 1;
-             scaled_ppm = -scaled_ppm;
-     }

Please don't re-write this logic.  It is written like that for a reason.

I used the sja1105_ptp.c as a reference. So it is also wrong there.

Hubert