ppc: clocksource doc vs. implementation?
mgl at doredevelopment.dk
Thu Nov 5 09:15:07 EST 2009
Working on porting to mpc83xx I've found that the ppc related part of
the porting.txt documentation seems to contradict the implementation for
Snip from Documentation/porting.txt:
- Add a clocksource for your system. PowerPCs have a generic decrementer
counter, so if you have a PowerPC aou have nothing to do here. on ARM
this is SoC dependend. See Documentation/timekeeping.txt for further
Snip from ppc/mach-mpc5xxx/start.S:
/* I guess we could implement decrementer, and may have
* to someday for timekeeping.
I couldn't find trace of any u-boot-v2 ppc code using the time base
decrementer or incrementer registers anywhere so I assume the time
keeping support for the current ppc is missing?
I assume that the correct course of action is to implement the
clocksource_read() function which reads out time counter using the
incrementing time base register?
Martin Lund, Senior Software Consultant
DoréDevelopment ApS, Ved Stranden 1, 9560 Hadsund, DK-Denmark
Phone: +45 51 92 84 24, Email: mgl at doredevelopment.dk
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