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>

2 files changed, 11 insertions, 18 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index cae9c3cb95cf..b79bd980461c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -762,10 +762,11 @@ extern void select_idle_routine(const struct cpuinfo_x86 *c);
 extern void init_c1e_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern unsigned long		idle_halt;
-extern unsigned long		idle_nomwait;
 extern bool			c1e_detected;
 
+enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
+			 IDLE_POLL, IDLE_FORCE_MWAIT};
+
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);
 
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 57d1868a86aa..b6472153e45b 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -22,11 +22,6 @@
 #include <asm/i387.h>
 #include <asm/debugreg.h>
 
-unsigned long idle_halt;
-EXPORT_SYMBOL(idle_halt);
-unsigned long idle_nomwait;
-EXPORT_SYMBOL(idle_nomwait);
-
 struct kmem_cache *task_xstate_cachep;
 EXPORT_SYMBOL_GPL(task_xstate_cachep);
 
@@ -328,7 +323,7 @@ long sys_execve(const char __user *name,
 /*
  * Idle related variables and functions
  */
-unsigned long boot_option_idle_override = 0;
+unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
 EXPORT_SYMBOL(boot_option_idle_override);
 
 /*
@@ -499,7 +494,6 @@ static void poll_idle(void)
  *
  * idle=mwait overrides this decision and forces the usage of mwait.
  */
-static int __cpuinitdata force_mwait;
 
 #define MWAIT_INFO			0x05
 #define MWAIT_ECX_EXTENDED_INFO		0x01
@@ -509,7 +503,7 @@ static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
-	if (force_mwait)
+	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
 		return 1;
 
 	if (c->cpuid_level < MWAIT_INFO)
@@ -629,9 +623,10 @@ static int __init idle_setup(char *str)
 	if (!strcmp(str, "poll")) {
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
-	} else if (!strcmp(str, "mwait"))
-		force_mwait = 1;
-	else if (!strcmp(str, "halt")) {
+		boot_option_idle_override = IDLE_POLL;
+	} else if (!strcmp(str, "mwait")) {
+		boot_option_idle_override = IDLE_FORCE_MWAIT;
+	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is
 		 * forced to be used for CPU idle. In such case CPU C2/C3
@@ -640,8 +635,7 @@ static int __init idle_setup(char *str)
 		 * the boot_option_idle_override.
 		 */
 		pm_idle = default_idle;
-		idle_halt = 1;
-		return 0;
+		boot_option_idle_override = IDLE_HALT;
 	} else if (!strcmp(str, "nomwait")) {
 		/*
 		 * If the boot option of "idle=nomwait" is added,
@@ -649,12 +643,10 @@ static int __init idle_setup(char *str)
 		 * states. In such case it won't touch the variable
 		 * of boot_option_idle_override.
 		 */
-		idle_nomwait = 1;
-		return 0;
+		boot_option_idle_override = IDLE_NOMWAIT;
 	} else
 		return -1;
 
-	boot_option_idle_override = 1;
 	return 0;
 }
 early_param("idle", idle_setup);