Re: [PATCH v6 2/9] Add driver cross timestamp interface for higher precision time synchronization

The series is a lot easier to follow now.  However, the
sync_device_time_cb structure isn't serving any useful purpose:

+/*
+ * struct get_sync_device_time_cb - Provides method to capture device time
+ *	synchronized with raw system counter value
+ * @get_time:	Callback providing synchronized capture of device time
+ *		and system counter. Returns 0 on success, < 0 on failure
+ * @ctx:	Context provided to callback function
+ */
+struct sync_device_time_cb {
+	int	(*get_time)(ktime_t *device_time,
+			    struct system_counterval_t *system_counterval,
+			    void *ctx);
+	void	 *ctx;
+};

Why not simply pass the function and context pointers as separate
arguments to get_device_system_crosststamp?

+/*
+ * Get cross timestamp between system clock and device clock
+ */
+extern int get_device_system_crosststamp(struct sync_device_time_cb *cb,
+					 struct system_device_crosststamp *ts);

Here is how it looks at the call site (from the last patch):

+static int e1000e_phc_getcrosststamp(struct ptp_clock_info *ptp,
+				     struct system_device_crosststamp *xtstamp)
+{
+	struct e1000_adapter *adapter = container_of(ptp, struct e1000_adapter,
+						     ptp_clock_info);
+	struct sync_device_time_cb sync_devicetime;
+	int ret;
+
+	sync_devicetime.get_time = e1000e_phc_get_syncdevicetime;
+	sync_devicetime.ctx = adapter;
+	ret = get_device_system_crosststamp(&sync_devicetime, NULL, xtstamp);
+	return ret;
+}

It is really just busy work to assign the fields of 'sync_devicetime'.
If you don't foresee the need of storing the sync_device_time_cb
object, then I would just remove the structure altogether.  Then the
call site will be cleaner, for example:

static int e1000e_phc_getcrosststamp(struct ptp_clock_info *ptp,
				     struct system_device_crosststamp *xtstamp)
{
	struct e1000_adapter *adapter = container_of(ptp, struct e1000_adapter,
						     ptp_clock_info);

	return get_device_system_crosststamp(e1000e_phc_get_syncdevicetime,
					     adapter, NULL, xtstamp);
}

Thanks,
Richard