diff options
| author | Zhao Yakui <yakui.zhao@intel.com> | 2008-06-24 17:58:53 +0800 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2008-07-16 23:27:05 +0200 |
| commit | c1e3b377ad48febba6f91b8ae42c44ee4d4ab45e (patch) | |
| tree | 7893e4226f52c4001150066f544415c1b17741f5 /drivers/acpi | |
| parent | 5b53496a5ad79e91052f72761a7c5516b069bc99 (diff) | |
ACPI: Create "idle=halt" bootparam
"idle=halt" limits the idle loop to using
the halt instruction. No MWAIT, no IO accesses,
no C-states deeper than C1.
If something is broken in the idle code,
"idle=halt" is a less severe workaround
than "idle=poll" which disables all power savings.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/processor_idle.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 0fc310e7dfd..c75c7ace8c1 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -41,6 +41,7 @@ #include <linux/pm_qos_params.h> #include <linux/clockchips.h> #include <linux/cpuidle.h> +#include <linux/cpuidle.h> /* * Include the apic definitions for x86 to have the APIC timer related defines @@ -57,6 +58,7 @@ #include <acpi/acpi_bus.h> #include <acpi/processor.h> +#include <asm/processor.h> #define ACPI_PROCESSOR_COMPONENT 0x01000000 #define ACPI_PROCESSOR_CLASS "processor" @@ -955,6 +957,17 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr) } else { continue; } + if (cx.type == ACPI_STATE_C1 && idle_halt) { + /* + * In most cases the C1 space_id obtained from + * _CST object is FIXED_HARDWARE access mode. + * But when the option of idle=halt is added, + * the entry_method type should be changed from + * CSTATE_FFH to CSTATE_HALT. + */ + cx.entry_method = ACPI_CSTATE_HALT; + snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT"); + } } else { snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x", cx.address); @@ -1780,6 +1793,15 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr, return 0; if (!first_run) { + if (idle_halt) { + /* + * When the boot option of "idle=halt" is added, halt + * is used for CPU IDLE. + * In such case C2/C3 is meaningless. So the max_cstate + * is set to one. + */ + max_cstate = 1; + } dmi_check_system(processor_power_dmi_table); max_cstate = acpi_processor_cstate_check(max_cstate); if (max_cstate < ACPI_C_STATES_MAX) |