[patch] Support for asymetrical per-cpu Cx states

[Stephane E. Potvin]

What started as a quick check why my laptop was not giving me Cx states
higher than C1 turned out in a major rework of the way the acpi_cpu
driver works.

The attached patch makes the following modifications to the driver:

- Support for asymetrical and per-cpu Cx states. This is done by parsing
the _CST packages for each cpu and tracking all the states individually,
on a per-cpu basis.

- Support to revert to generic FADT/P_BLK based Cx control if the _CST
package are not present on all cpus. In that case, the new driver will
still support per-cpu Cx state handling. The driver will determine the
highest Cx level that can be supported by all the cpus and configure the
available Cx state based on that.

- Fixed the case where multiple cpus in the system share the same
registers for Cx state handling. To do that, I added a new flag
parameter to the acpi_PkgGas and acpi_bus_alloc_gas functions that
enable the caller to add the RF_SHAREABLE flag. This will probably fix
the case where enabling the HT core would remove all Cx states (except
C1), but I have no mean to check it at this time. I've not added this
flag to the other callers in the tree but I guess that some of them
could use this flag when multiple cpus are present.

- I also found out that for Core Duo cpus, both cores seems to be taken
out of C3 state when any one of the cores need to transition out. This
broke the short sleep detection logic. I disabled it if there are more
than one cpu in the system for now as it fixed it in my case. I guess
that proper quirks handling will be required to fix this for known non
working systems.

- Added support to control cx_lowest on a per-cpu basis. I also
implemented a generic cx_lowest to enable changing cx_lowest for all
cpus with a single sysctl and for backward compatibility. The value
returned on read is kind of meaningless (is there an easy way to have a
write-only sysctl?) I've not done the same for the cx_supported case as
I was not sure which way to handle it in case all supported Cx states
were not symmetrical. Sample output for the new sysctl:

hw.acpi.cpu.0.cx_supported: C1/1 C2/1 C3/57
hw.acpi.cpu.0.cx_lowest: C3
hw.acpi.cpu.0.cx_usage: 0.00% 43.16% 56.83%
hw.acpi.cpu.1.cx_supported: C1/1 C2/1 C3/57
hw.acpi.cpu.1.cx_lowest: C3
hw.acpi.cpu.1.cx_usage: 0.00% 45.65% 54.34%
hw.acpi.cpu.cx_lowest: C3

I would appreciate any feedback, positive or negative, on this :)

Steph

-------------- next part --------------
A non-text attachment was scrubbed...
Name: acpi_cpu.diff
Type: text/x-patch
Size: 31918 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-acpi/attachments/20060607/7004ed3e/acpi_cpu.bin