timer unit of Allwinner A64 UNKNOWN1 bug

timer unit of Allwinner A64 UNKNOWN1 bug

[Ilya Dikariev]

[-- Attachment #1: Type: text/plain, Size: 510 bytes --]

Hello all,

owned a Pinephone and it turns out, that the genmask(8,0) is not
sufficient to get a workaround in this particular case.

The phone get freezed pretty often, and after some 10-15 minutes
unfreezes. Time jumps too.

Did the test https://github.com/smaeul/timer-tools that resulted in
https://pastebin.com/xbTeksJN


After applying the patch (changing to genmask(7,0)) the test passed. No
errors within hours and no freezes/time jumps.

Could you implement this into a mainline?

Best regards,
Ilya


[-- Attachment #2: rcu.patch --]
[-- Type: text/x-patch, Size: 433 bytes --]

--- a/drivers/clocksource/arm_arch_timer.c	2022-11-03 12:55:50.149533030 +0100
+++ b/drivers/clocksource/arm_arch_timer.c	2022-11-03 12:56:25.309720213 +0100
@@ -371,7 +371,7 @@
 	do {								\
 		_val = read_sysreg(reg);				\
 		_retries--;						\
-	} while (((_val + 1) & GENMASK(8, 0)) <= 1 && _retries);	\
+	} while (((_val + 1) & GENMASK(7, 0)) <= 1 && _retries);	\
 									\
 	WARN_ON_ONCE(!_retries);					\
 	_val;								\

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