Re: [PATCH] - Initial dothan speedstep support
From: Michael Clark
Date: Sun Aug 22 2004 - 19:33:50 EST
On 08/22/04 15:31, Clark, Michael wrote:
Hi!
So here's a patch on top of the above patch that adds all of the
dothan frequency/voltages for processors 715, 725, 735, 745, 755
Tested and working as it should so far with a 745. The stepping in the
model table for the others may need to be tweaked.
The Dothan processor datasheet 30218903.pdf defines 4 voltages for
each frequency (VID#A through VID#D) whereas Banias only suggests a
typical voltage and no min or max for each freq so i've used the OP
macro to allow definition of all voltages (A through D) but the macro
currently just uses VID#C at compile time (the second lowest voltage
profile).
I thought that whether to use VID#A, B, C or D depends on
your concrete chip? Not all chips are certified to run on VID#C...
Yes, I believe this is the case. When I read the processor spec
document it did not mention this but since then i found this out. I've
since changed the patch to use the VID#A voltages which is more
conservative (assuming that all of them will run at the higher voltage
okay which according to the upper voltage rating of 1.6 volts might be
On re-looking at the spec and the voltage tolerance tables in particular
I realize my approach is not valid. A VID#B can be driven at VID#A
voltages but there is no voltage in common for some frequencies between
all VID# variants.
okay). It would of course be preferrable to work out the the type
VID#A,B,C,D via software - not sure if this is possible.
Perhaps the VID# variant can be found via MSRs - if not the static tables
will not be workable and the ACPI approach will have to be the sole method.
~mc
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