[ltt-dev] OMAP3/4 trace clock and lockdep tracing

Harald Gustafsson hgu1972 at gmail.com
Fri Apr 8 04:55:54 EDT 2011

I took a look at the Linaro lttng git, but they don't seem to have
adopted it more for the OMAP4 than in your git tree. There is a new
pm44xx.c file which don't contain any resync_trace_clock() calls which
should be needed and the trace-clock.c file is your ordinary one.

2011/4/7 Mathieu Desnoyers <compudj at krystal.dyndns.org>:
> Please note that you can be woken up by an interrupt, which means that
> an IRQ handler will be executed before you resume to execute the
> instruction that follows the WFI. Do you resync when woken up by these
> interrupts ?
No, which might be causing the issues, but do you resync in the IRQ
for OMAP3 I could not find any code that did that? rather the comment
saying that IRQ might have run before the call to the resync in the
pm34xx.c file.

>>       clock_val = cnt32_to_63(clock32k->read(clock32k)) << TRACE_CLOCK_32K_BITSHIFT;
> You might want to use the trace clock 32 to 64 provided by LTTng instead
> of cnt_32_to_63. See the kernel/trace/trace-clock-32-to-64.c.

I did consider the trace-clock-32-to-64.c but decided that it was
overkill for extending a continuous running low rate clock, the
cnt32_to_63 macro in include/linux/cnt32_to_63.h is commonly used to
extend counters at least on ARM arch.


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