From 0842ca056554ac01c0a2c0770496291ca76d4480 Mon Sep 17 00:00:00 2001
From: The-going <48602507+The-going@users.noreply.github.com>
Date: Fri, 28 Jan 2022 14:18:17 +0300
Subject: [PATCH 4/8] drv:clocksource:arm_arch_timer fix a64 timejump

---
 drivers/clocksource/arm_arch_timer.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index be6d741d4..ffc42573a 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -357,17 +357,20 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
  * with all ones or all zeros in the low bits. Bound the loop by the maximum
  * number of CPU cycles in 3 consecutive 24 MHz counter periods.
  */
-#define __sun50i_a64_read_reg(reg) ({					\
-	u64 _val;							\
-	int _retries = 150;						\
-									\
-	do {								\
-		_val = read_sysreg(reg);				\
-		_retries--;						\
-	} while (((_val + 1) & GENMASK(8, 0)) <= 1 && _retries);	\
-									\
-	WARN_ON_ONCE(!_retries);					\
-	_val;								\
+#define __sun50i_a64_read_reg(reg) ({                                                 \
+    register u64 _tries = 5, _old, _new;                                              \
+                                                                                      \
+    do {                                                                              \
+        if (unlikely(_tries < 3))                                                     \
+            isb();                                                                    \
+        _old = read_sysreg(reg);                                                      \
+        _new = read_sysreg(reg);                                                      \
+    } while (unlikely((_new - _old) >> 4) && --_tries);                               \
+                                                                                      \
+    if (unlikely(!_tries))                                                            \
+        pr_err("(cpu %d) returning possibly incorrect counter value %llx (%llx)\n",   \
+                smp_processor_id() + 1, _new, _old);                                  \
+   _new;                                                                              \
 })
 
 static u64 notrace sun50i_a64_read_cntpct_el0(void)
-- 
2.31.1