Martin Mares writes:
> Proper calculation of latency timers is a very complex and arcane thing
> which requires knowledge of bus speed, arbitration algorithm used by the
> central bus arbiter, latencies of non-PCI devices in the system and so on.
> I plan to write a user-space utility trying to guess all these parameters
> and calculate the appropriate latencies, but I would like to keep it outside
> the kernel unless unavoidable. (As DaveM has already mentioned, this already
> very complex task is further complicated by many devices reporting invalid
> MIN_GNT/MAX_LAT values...)
This would also be useful for machines which don't have a BIOS as such
as well. However, looking at a few sets of lspci -vv outputs, it appears
that there isn't any real method by which they are initialised. From
the data I've seen, many systems just initialise the latency timers to
32 and that's it. Of course, they could be excellent illustrations of
broken BIOSes.
_____
|_____| ------------------------------------------------- ---+---+-
| | Russell King rmk@arm.linux.org.uk --- ---
| | | | http://www.arm.linux.org.uk/~rmk/aboutme.html / / |
| +-+-+ --- -+-
/ | THE developer of ARM Linux |+| /|\
/ | | | --- |
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