From: Arjan van de Ven <[EMAIL PROTECTED]>
Taken from http://bugzilla.kernel.org/show_bug.cgi?id=8703
Cc: Dag Bakke <[EMAIL PROTECTED]>
Cc: Len Brown <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
drivers/acpi/processor_idle.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)
diff -puN
drivers/acpi/processor_idle.c~acpi-enable-c3-power-state-on-dell-inspiron-8200
drivers/acpi/processor_idle.c
---
a/drivers/acpi/processor_idle.c~acpi-enable-c3-power-state-on-dell-inspiron-8200
+++ a/drivers/acpi/processor_idle.c
@@ -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},
{},
};
@@ -487,11 +506,12 @@ 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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