Messages in this thread | | | Date | Thu, 7 Jul 2005 23:59:28 +0200 | From | st3@riseup ... | Subject | Re: speedstep-centrino on dothan |
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On Wed, 06 Jul 2005 15:58:53 -0400 Bill Davidsen <davidsen@tmr.com> wrote:
> st3@riseup.net wrote:
[snip]
> > Moreover, I checked on Pentium M 725 and Pentium M 715 that the lowest > > frequency at which the CPU can be set safely is not the 600MHz given in > > datasheets, but 400MHz instead, with VID#A, VID#B, VID#C and VID#D (see > > datasheet for more details) set to 0.908V. > > > > I can provide a patch, let me know. > > Slower is better
[snip]
Here's a quick trick for getting CPU to lower frequencies than the ones read from ACPI tables, while still keeping them available.
Just add these lines in centrino_cpu_init_acpi(), in speedstep-centrino.c, just after (and outside) the first 'for' cycle like this: for (i=0; i<p.state_count; i++) { ...
centrino_model[cpu]->op_points[p.state_count - 1].index = 0x040D; centrino_model[cpu]->op_points[p.state_count - 1].frequency = 400000; p.states[p.state_count - 1].core_frequency = 400;
This will enable 400MHz at 908mV, which I found to be useful on Dothan CPUs. If you want to get values for other frequencies/voltages, just use something like:
#include <stdio.h>
int main() { unsigned int index, frequency, voltage
index = (((frequency)/100) << 8) | ((voltage - 700) / 16); printf ("%u\n", index); }
frequency is expressed in MHz, voltage in mV, index is the value for centrino_model[cpu]->op_points[y].index <- remember to change this y if you want to add multiple frequencies besides the ACPI ones; for example, if you want 500MHz at 940mV, you could add:
centrino_model[cpu]->op_points[p.state_count - 2].index = 0x1295; centrino_model[cpu]->op_points[p.state_count - 2].index = 500000; p.states[p.state_count - 2].core_frequency = 500;
Sorry if I have been off-topic.
-- ciao st3
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