Does this system have a _CST in its DSDT?
Can you attach the output of acpidump to a bugzilla.kernel.org entry?
Also, the complete output from dmesg -s64000
thanks,
-Len
On Monday 25 June 2007 16:25, Dag Bakke wrote:
> The attached patch makes the kernel ignore the fact that P_LVL3_LAT is
> set to 2000 in the relevant ACPI table, and enforces the C3 power state
> anyway. I have not observed any ill effects with this patch on my
> P4m-equipped Inspiron 8200, and would like to see this patch applied
> upstream.
>
> It saves ~2.5 watts on an idle system, so should be well worth it.
>
> The patch was written by Arjan van de Ven based on my initial tests, and
> the patch has been tested by myself.
> It applies to 2.6.22-rc5 and likely also -rc6.
>
>
> Dag Bakke
>
>
> Tested-by: Dag Bakke <dag@xxxxxxxxx>
>
> --- linux/drivers/acpi/processor_idle.c.org 2007-06-10
> 14:18:27.000000000 -0700
> +++ linux/drivers/acpi/processor_idle.c 2007-06-10 14:27:45.000000000 -0700
> @@ -67,6 +67,8 @@ ACPI_MODULE_NAME("processor_idle");
> #define C2_OVERHEAD 1 /* 1us */
> #define C3_OVERHEAD 1 /* 1us */
>
> +static int forced_c3;
> +
> void acpi_max_cstate_changed(void)
> {
> /* Driver will reset devices' max cstate limit */
> @@ -115,6 +117,20 @@ static int set_max_cstate(struct dmi_sys
> return 0;
> }
>
> +/*
> + * Some (Dell) machines have a too large C3 latency set, but it still
> works completely.
> + * Dell provides a driver for other operating systems to hack around
> this bug, so we know
> + * it's safe.
> + */
> +static int dmi_force_c3(struct dmi_system_id *id)
> +{
> + forced_c3 = 1;
> +
> + printk(KERN_NOTICE PREFIX "%s detected - Force enabling C3.", id->ident);
> +
> + return 0;
> +}
> +
> /* Actually this shouldn't be __cpuinitdata, would be better to fix the
> callers to only run once -AK */
> static struct dmi_system_id __cpuinitdata processor_power_dmi_table[] = {
> @@ -173,6 +189,9 @@ static struct dmi_system_id __cpuinitdat
> DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
> DMI_MATCH(DMI_BIOS_VERSION,"SHE845M0.86C.0013.D.0302131307")},
> (void *)2},
> + { dmi_force_c3, "Dell Inspiron 8200", {
> + DMI_MATCH(DMI_SYS_VENDOR,"Dell Computer Corporation"),
> + DMI_MATCH(DMI_PRODUCT_NAME,"Inspiron 8200") }, NULL},
> {},
> };
>
> @@ -474,11 +493,12 @@ static void acpi_processor_power_verify_
> * C3 latency must be less than or equal to 1000
> * microseconds.
> */
> - else if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
> + if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY && !forced_c3) {
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "latency too large [%d]\n", cx->latency));
> return;
> - }
> + } else if (forced_c3)
> + cx->latency = ACPI_PROCESSOR_MAX_C3_LATENCY;
>
> /*
> * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
> -
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