[coreboot] Howto enable AMD Cool'n'Quiet support

[Rudolf Marek]

Hi,

Sorry for the delay.> CPU ID 0x80000001: fc0

So your CPU is revision "DH" which is pre "F".

> But I have also seen that CONFIG_K8_REV_F_SUPPORT is not set in .config

nope this is for some other CPUs.

If you look to coreboot/src/cpu/amd/model_fxx/powernow_acpi.c, your CPU 0xfc0
has an entry there.

You need to check pstates_algorithm() function. It may not be executed at all,
or there is something wrong with that. Make sure that you look to the later one,
there is #ifdef in this file! The first one is for CONFIG_K8_REV_F_SUPPORT.

This functionality is called from amd_generate_powernow()
which goes from via/k8t890/traf_ctrl.c

I suspect that this old VIA chipset has no PCI device for this thus the

.acpi_fill_ssdt_generator = southbridge_acpi_fill_ssdt_generator

Is never called. I did not do the support for the K8T800 chipset so I don't
know. Maybe you can provide lspci -xxx -n from linux to see what kind of PCI
devices you have. Perhaps then the callback can be added elsewhere to the PCI
device you have such as  northbridge_driver_t800_old.

You can try attached patch, maybe it will move you further. I remember it was
real pain to get the cool-n-quiet working, there was a lot of southbridge tweaks
necessary (and undocumented bits!). Just give it a try. In worst case you will
see some messages in dmesg about Targ stuck bits...

Thanks
Rudolf


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