From 354ccf64bf5c5cc2d3276575f6f5537864dc3af8 Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Sat, 23 Dec 2023 18:52:17 -0500
Subject: [PATCH] iicbb: Fix pause_sbt() arguments order

It should make pause interval less strict.

While there, add cpu_spinwait() into a tight spin wait loop to burn
less power and let other SMT thread work more.

MFC after:	1 month

(cherry picked from commit a74df3f96e3ea4cc632088be870d9b0b0198859c)
---
 sys/dev/iicbus/iicbb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sys/dev/iicbus/iicbb.c b/sys/dev/iicbus/iicbb.c
index 3948d5d5a9f..5d6ac48d454 100644
--- a/sys/dev/iicbus/iicbb.c
+++ b/sys/dev/iicbus/iicbb.c
@@ -52,6 +52,7 @@
 #include <sys/bus.h>
 #include <sys/sysctl.h>
 #include <sys/uio.h>
+#include <machine/cpu.h>
 
 #ifdef FDT
 #include <dev/ofw/ofw_bus.h>
@@ -254,11 +255,12 @@ iicbb_waitforscl(device_t dev)
 	do {
 		if (I2C_GETSCL(dev))
 			return (0);
+		cpu_spinwait();
 		now = sbinuptime();
 	} while (now < fast_timeout);
 	do {
 		I2C_DEBUG(printf("."));
-		pause_sbt("iicbb-scl-low", SBT_1MS, C_PREL(8), 0);
+		pause_sbt("iicbb-scl-low", SBT_1MS, 0, C_PREL(2));
 		if (I2C_GETSCL(dev))
 			return (0);
 		now = sbinuptime();