Re: C states on AMD SMP

Pavel Troller
2005-09-08T11:52:06Z

> Hi,
>
> I compiled & installed 2.6.13 (vanilla) on my Tyan Tiger S2466 (AMD768
> chipset, 2xathlon MP 2600) yesterday. Indeed, as expected, acpi
> "/proc/acpi/processor/*/power" (C states) is now supported on SMP. But,
> to my surprise, it only shows one C state (C1), which, I assume, is
> full-on. I am not completely sure about the CPU, but I do know that at
> least the chipset supports C2 and C3 states (even got it sort of working
> with pm_amd76x).
>
> Can someone shine some light on this?
>
> active state: C1
> max_cstate: C8
> bus master activity: 00000000
> states:
> *C1: type[C1] promotion[--] demotion[--] latency[000] usage[59379522]
>
Hi!
I have MSI K7D Master with the same chipset and the same problem :-).
Try to dump Your FADT. Mine is as follows:

# cat /proc/acpi/fadt | acpitbl
Signature: FACP
Length: 244
Revision: 0x01
Checksum: 0x5f
OEMID: AMD2P
OEM Table ID: AWRDACPI
OEM Revision: 0x42302e31
Creator ID: AWRD
Creator Revision: 0x00000000
FIRMWARE_CTRL: 0x1fff0000
DSDT: 0x1fff30c0
INT_MODEL: 0x01
SCI_INT: 9
SMI_CMD: 0x0000062f
ACPI_ENABLE: 0xa1
ACPI_DISABLE: 0xa0
S4BIOS_REQ: 0x00
PM1a_EVT_BLK: 0x00000600
PM1b_EVT_BLK: 0x00000000
PM1a_CNT_BLK: 0x00000604
PM1b_CNT_BLK: 0x00000000
PM2_CNT_BLK: 0x00000000
PM_TMR_BLK: 0x00000608
GPE0_BLK: 0x00000620
GPE1_BLK: 0x00000000
PM1_EVT_LEN: 4
PM1_CNT_LEN: 2
PM2_CNT_LEN: 0
PM_TM_LEN: 4
GPE0_BLK_LEN: 4
GPE1_BLK_LEN: 0
GPE1_BASE: 0
P_LVL2_LAT: 101
P_LVL3_LAT: 1001
FLUSH_SIZE: 0
FLUSH_STRIDE: 0
DUTY_OFFSET: 1
DUTY_WIDTH: 1
DAY_ALRM: 0x7d
MON_ALRM: 0x7e
CENTURY: 0x7f
Flags: 0x00000000

Do You see ? P_LVL2_LAT is 101 and P_LVL3_LAT is 1001, exactly 1 ms ABOVE the
maximum stated in the ACPI spec as allowed. Somebody at Tyan (or MSI in my
case) decided to disable generic C2/C3 support. Maybe because the chipset
requires more care to handle the C2/C3 states than described in the ACPI spec.

I'm using pm_amd76x regularly too, and it works perfectly!
Regards, Pavel Troller

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