[coreboot] Patch merged into coreboot/master: 4fc6004 AMD Fam14 boards: Set P_BLK length to 6 for all processors

the following patch was just integrated into master:
commit 4fc600442b578e3e79acb221040638ab52f600ed
Author: Paul Menzel 
Date:   Mon Jan 21 18:43:12 2013 +0100

AMD Fam14 boards: Set P_BLK length to 6 for all processors

Currently on for example on AMD Persimmon and ASRock E350M1 Linux
    complains, that the PBLK length is invalid [1].

ACPI: Invalid PBLK length [0]

Consequently, frequency scaling might not work correctly, though for
    these two boards it seems to work according to PowerTOP.

Indeed, according to the ACPI specification [2], setting PBlockLength
    to 0 is only allowed if there is no PBlockAddress. Otherwise it has to
    be set to 6.

18.5.93 Processor (Declare Processor)

[…]

PBlockAddress provides the system I/O address for the processors
            register block. Each processor can supply a different such
            address. PBlockLength is the length of the processor register
            block, in bytes and is either 0 (for no P_BLK) or 6. With one
            exception, all processors are required to have the same
            PBlockLength. The exception is that the boot processor can have
            a non-zero PBlockLength when all other processors have a zero
            PBlockLength. It is valid for every processor to have a
            PBlockLength of 0.

And that is exactly what Linux is checking in
    `drivers/acpi/processor_driver.c` [3].

static int acpi_processor_get_info(struct acpi_device *device)
            {
            […]
                    /*
                     * On some boxes several processors use the same processor bus id.
                     * But they are located in different scope. For example:
                     * _SB.SCK0.CPU0
                     * _SB.SCK1.CPU0
                     * Rename the processor device bus id. And the new bus id will be
                     * generated as the following format:
                     * CPU+CPU ID.
                     */
                    sprintf(acpi_device_bid(device), "CPU%X", pr->id);
                    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Processor [%d:%d]\n", pr->id,
                                      pr->acpi_id));

if (!object.processor.pblk_address)
                            ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
                    else if (object.processor.pblk_length != 6)
                            printk(KERN_ERR PREFIX "Invalid PBLK length [%d]\n",
                                        object.processor.pblk_length);
                    else {
                            pr->throttling.address = object.processor.pblk_address;
                            pr->throttling.duty_offset = acpi_gbl_FADT.duty_offset;
                            pr->throttling.duty_width = acpi_gbl_FADT.duty_width;

pr->pblk = object.processor.pblk_address;

/*
                             * We don't care about error returns - we just try to mark
                             * these reserved so that nobody else is confused into thinking
                             * that this region might be unused..
                             *
                             * (In particular, allocating the IO range for Cardbus)
                             */
                            request_region(pr->throttling.address, 6, "ACPI CPU throttle");
                    }
            […]
            }

This issue has proliferated to all AMD based boards so fix it for
    all of them by setting P_BLK length to 6.

The DSDT of for example AMD Parmer and AMD Thatcher also set it
    to 6 everywhere so this solution is taken instead of setting the
    P_BLK system I/O base to 0 for all but the first processor which
    is how it is done for earlier AMD based boards.

As note having to set this manually should not be needed and
    this should be autogenerated as done for most of the Intel boards
    and the AMD K8 based boards (`src/cpu/amd/model_fxx/powernow_acpi.c`).

[1] http://www.coreboot.org/pipermail/coreboot/2013-January/073636.html
    [2] http://acpi.info/DOWNLOADS/ACPIspec40a.pdf
    [3] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=driver...

Tested-by: Paul Menzel 
    • ASRock E350M1:
    Tested-by: Paul Menzel 
    • AMD Persimmon:
    Tested-by: Martin Roth 
    Change-Id: Ie79fe4812532d124cc81747c75a4f3d88d00531c
    Signed-off-by: Paul Menzel 
    Reviewed-on: http://review.coreboot.org/2189
    Tested-by: build bot (Jenkins)
    Reviewed-by: Martin Roth

Build-Tested: build bot (Jenkins) at Fri Feb 22 23:16:09 2013, giving +1
See http://review.coreboot.org/2189 for details.

-gerrit