acpi_cpu: _PDC vs _OSC

[John Baldwin]

On Thursday 04 February 2010 2:42:47 pm Andriy Gapon wrote:
> 
> Below is the patch that I have.
> _PDC is evaluated only if _OSC evaluation fails.
> _OSC status returned by AML is reported if not zero.
> Small changes in comments.
> 
> BTW, 'if (sc->cpu_features)' check could probably be dropped, because we
> initialize cpu_features with non-zero value and then only bit-or to it.
> 
> Index: sys/dev/acpica/acpi_cpu.c
> ===================================================================
> --- sys/dev/acpica/acpi_cpu.c	(revision 203497)
> +++ sys/dev/acpica/acpi_cpu.c	(working copy)
> @@ -345,26 +345,13 @@
>      }
> 
>      /*
> -     * CPU capabilities are specified as a buffer of 32-bit integers:
> -     * revision, count, and one or more capabilities.  The revision of
> -     * "1" is not specified anywhere but seems to match Linux.
> +     * CPU capabilities are specified in
> +     * Intel Processor Vendor-Specific ACPI Interface Specification.
>       */
>      if (sc->cpu_features) {
> -	arglist.Pointer = arg;
> -	arglist.Count = 1;
> -	arg[0].Type = ACPI_TYPE_BUFFER;
> -	arg[0].Buffer.Length = sizeof(cap_set);
> -	arg[0].Buffer.Pointer = (uint8_t *)cap_set;
> -	cap_set[0] = 1; /* revision */
> -	cap_set[1] = 1; /* number of capabilities integers */
> -	cap_set[2] = sc->cpu_features;
> -	AcpiEvaluateObject(sc->cpu_handle, "_PDC", &arglist, NULL);
> -
>  	/*
> -	 * On some systems we need to evaluate _OSC so that the ASL
> -	 * loads the _PSS and/or _PDC methods at runtime.
> -	 *
> -	 * TODO: evaluate failure of _OSC.
> +	 * On some systems evaluation of _OSC/_PDC dynamically
> +	 * loads the _PSS and other methods.
>  	 */

I would only say _OSC here.  I don't think we've seen any systems that load 
something when _PDC is invoked, only when _OSC is invoked.

-- 
John Baldwin