--- dahdi-linux-complete-3.1.0+3.1.0/linux/drivers/dahdi/dahdi-sysfs.c	2019-10-03 21:48:09.000000000 +0700
+++ dahdi-linux-complete/linux/drivers/dahdi/dahdi-sysfs.c	2020-08-17 19:26:34.186150611 +0700
@@ -654,7 +654,15 @@
 {
 	struct dahdi_device *ddev = to_ddev(dev);
 	int count = 0;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
 	struct timespec64 ts = ktime_to_timespec64(ddev->registration_time);
+#else
+	/* ktime_to_timespec64 was added to Linux 3.17.
+	Moreover, ktime could be scalar, or "optimized". See CONFIG_KTIME_SCALAR.
+	Sure, untill 2038 DAHDI will remove support for kernels older than 3.17,
+	so, let's just use old ktime_to_timespec for old kernels. */
+	struct timespec ts = ktime_to_timespec(ddev->registration_time);
+#endif
 
 	count += sprintf(buf, "%010lld.%09ld\n",
 		(s64)ts.tv_sec,