[PATCH] RFC: arm64: arch_timer: Fix timer inconsistency test for A64

Roman Stratiienko
2020-09-29T11:15:28Z

Fixes linux_kselftest:timers_inconsistency-check_arm_64

Test logs without the fix:
'''
binary returned non-zero. Exit code: 1, stderr: , stdout:
Consistent CLOCK_REALTIME
1601335525:467086804
1601335525:467087554
1601335525:467088345
1601335525:467089095
1601335525:467089887
1601335525:467090637
1601335525:467091429
1601335525:467092179
1601335525:467092929
1601335525:467093720
1601335525:467094470
1601335525:467095262
1601335525:467096012
1601335525:467096804
--------------------
1601335525:467097554
1601335525:467077012
--------------------
1601335525:467099095
1601335525:467099845
1601335525:467100637
1601335525:467101387
1601335525:467102179
1601335525:467102929
'''

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
CC: linux-arm-kernel@lists.infradead.org
CC: linux-kernel@vger.kernel.org
CC: linux-sunxi@googlegroups.com
CC: megous@megous.com
---
drivers/clocksource/arm_arch_timer.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6c3e841801461..d50aa43cb654b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -346,16 +346,17 @@ static u64 notrace arm64_858921_read_cntvct_el0(void)
* number of CPU cycles in 3 consecutive 24 MHz counter periods.
*/
#define __sun50i_a64_read_reg(reg) ({ \
- u64 _val; \
+ u64 _val1, _val2; \
int _retries = 150; \
\
do { \
- _val = read_sysreg(reg); \
+ _val1 = read_sysreg(reg); \
+ _val2 = read_sysreg(reg); \
_retries--; \
- } while (((_val + 1) & GENMASK(9, 0)) <= 1 && _retries); \
+ } while (((_val2 - _val1) > 0x10) && _retries); \
\
WARN_ON_ONCE(!_retries); \
- _val; \
+ _val2; \
})

static u64 notrace sun50i_a64_read_cntpct_el0(void)
--
2.25.1