ACPI, intel_idle: Cleanup idle= internal variables

Having four variables for the same thing:
  idle_halt, idle_nomwait, force_mwait and boot_option_idle_overrides
is rather confusing and unnecessary complex.

if idle= boot param is passed, only set up one variable:
boot_option_idle_overrides

Introduces following functional changes/fixes:
  - intel_idle driver does not register if any idle=xy
    boot param is passed.
  - processor_idle.c will also not register a cpuidle driver
    and get active if idle=halt is passed.
    Before a cpuidle driver with one (C1, halt) state got registered
    Now the default_idle function will be used which finally uses
    the same idle call to enter sleep state (safe_halt()), but
    without registering a whole cpuidle driver.

That means idle= param will always avoid cpuidle drivers to register
with one exception (same behavior as before):
idle=nomwait
may still register acpi_idle cpuidle driver, but C1 will not use
mwait, but hlt. This can be a workaround for IO based deeper sleep
states where C1 mwait causes problems.

Signed-off-by: Thomas Renninger <trenn@suse.de>
cc: x86@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>

3 files changed, 17 insertions, 15 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index bec561c14beb..3c1a2fec8cda 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -23,7 +23,7 @@ static int set_no_mwait(const struct dmi_system_id *id)
 {
 	printk(KERN_NOTICE PREFIX "%s detected - "
 		"disabling mwait for CPU C-states\n", id->ident);
-	idle_nomwait = 1;
+	boot_option_idle_override = IDLE_NOMWAIT;
 	return 0;
 }
 
@@ -283,7 +283,7 @@ acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
 {
 	acpi_status status = AE_OK;
 
-	if (idle_nomwait) {
+	if (boot_option_idle_override == IDLE_NOMWAIT) {
 		/*
 		 * If mwait is disabled for CPU C-states, the C2C3_FFH access
 		 * mode will be disabled in the parameter of _PDC object.
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index dcb38f8ddfda..eefd4aa0e71d 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -79,6 +79,13 @@ module_param(bm_check_disable, uint, 0000);
 static unsigned int latency_factor __read_mostly = 2;
 module_param(latency_factor, uint, 0644);
 
+static int disabled_by_idle_boot_param(void)
+{
+	return boot_option_idle_override == IDLE_POLL ||
+		boot_option_idle_override == IDLE_FORCE_MWAIT ||
+		boot_option_idle_override == IDLE_HALT;
+}
+
 /*
  * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
  * For now disable this. Probably a bug somewhere else.
@@ -455,7 +462,7 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
 				continue;
 			}
 			if (cx.type == ACPI_STATE_C1 &&
-					(idle_halt || idle_nomwait)) {
+			    (boot_option_idle_override == IDLE_NOMWAIT)) {
 				/*
 				 * In most cases the C1 space_id obtained from
 				 * _CST object is FIXED_HARDWARE access mode.
@@ -1058,7 +1065,7 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
 {
 	int ret = 0;
 
-	if (boot_option_idle_override)
+	if (disabled_by_idle_boot_param())
 		return 0;
 
 	if (!pr)
@@ -1089,19 +1096,10 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
 	acpi_status status = 0;
 	static int first_run;
 
-	if (boot_option_idle_override)
+	if (disabled_by_idle_boot_param())
 		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)
@@ -1142,7 +1140,7 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
 int acpi_processor_power_exit(struct acpi_processor *pr,
 			      struct acpi_device *device)
 {
-	if (boot_option_idle_override)
+	if (disabled_by_idle_boot_param())
 		return 0;
 
 	cpuidle_unregister_device(&pr->power.dev);
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 94a652625ae2..21d387132dbc 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -404,6 +404,10 @@ static int __init intel_idle_init(void)
 {
 	int retval;
 
+	/* Do not load intel_idle at all for now if idle= is passed */
+	if (boot_option_idle_override != IDLE_NO_OVERRIDE)
+		return -ENODEV;
+
 	retval = intel_idle_probe();
 	if (retval)
 		return retval;