On 19/01/2017 14:35, Ding Tianhong wrote:

Erratum Hisilicon-161010101 says that the ARM generic timer counter "has the
potential to contain an erroneous value when the timer value changes".
Accesses to TVAL (both read and write) are also affected due to the implicit counter
read.  Accesses to CVAL are not affected.

The workaround is to reread the system count registers until the value of the second
read is larger than the first one by less than 32, the system counter can be guaranteed
not to return wrong value twice by back-to-back read and the error value is always larger
than the correct one by 32. Writes to TVAL are replaced with an equivalent write to CVAL.

Why not use another clocksource instead of adding a workaround with a
non negligible overhead and more complexity in the code ?


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