--- zzzz-none-000/linux-5.4.213/include/linux/delay.h	2022-09-15 10:04:56.000000000 +0000
+++ alder-5690pro-762/linux-5.4.213/include/linux/delay.h	2024-08-14 09:02:08.000000000 +0000
@@ -65,4 +65,15 @@
 	msleep(seconds * 1000);
 }
 
+/* see Documentation/timers/timers-howto.rst for the thresholds */
+static inline void fsleep(unsigned long usecs)
+{
+	if (usecs <= 10)
+		udelay(usecs);
+	else if (usecs <= 20000)
+		usleep_range(usecs, 2 * usecs);
+	else
+		msleep(DIV_ROUND_UP(usecs, 1000));
+}
+
 #endif /* defined(_LINUX_DELAY_H) */