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cpuidle acpi driver: fix oops on AC<->DC

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cpuidle and acpi driver interaction bug with the way cpuidle_register_driver()
is called. Due to this bug, there will be oops on
AC<->DC on some systems, where they support C-states in one DC and not in AC.

The current code does
ON BOOT:
	Look at CST and other C-state info to see whether more than C1 is
	supported. If it is, then acpi processor_idle does a
	cpuidle_register_driver() call, which internally enables the device.

ON CST change notification (AC<->DC) and on suspend-resume:
	acpi driver temporarily disables device, updates the device with
	any new C-states, and reenables the device.

The problem is is on boot, there are no C2, C3 states supported and we skip
the register. Later on AC<->DC, we may get a CST notification and we try
to reevaluate CST and enabled the device, without actually registering it.
This causes breakage as we try to create /sys fs sub directory, without the
parent directory which is created at register time.

Thanks to Sanjeev for reporting the problem here.
http://bugzilla.kernel.org/show_bug.cgi?id=10394

Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Len Brown <[email protected]>
This commit is contained in:
Venkatesh Pallipadi 2008-05-19 19:09:27 -04:00 • committed by Len Brown
commit dcb84f335b
3 changed files with 43 additions and 11 deletions
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13
drivers/acpi/processor_idle.c
View file

@ -1669,6 +1669,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
return -EINVAL;
}
dev->cpu = pr->id;
for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
dev->states[i].name[0] = '\0';
dev->states[i].desc[0] = '\0';
@ -1738,7 +1739,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
int acpi_processor_cst_has_changed(struct acpi_processor *pr)
{
int ret;
int ret = 0;
if (boot_option_idle_override)
return 0;
@ -1756,8 +1757,10 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
cpuidle_pause_and_lock();
cpuidle_disable_device(&pr->power.dev);
acpi_processor_get_power_info(pr);
acpi_processor_setup_cpuidle(pr);
ret = cpuidle_enable_device(&pr->power.dev);
if (pr->flags.power) {
acpi_processor_setup_cpuidle(pr);
ret = cpuidle_enable_device(&pr->power.dev);
}
cpuidle_resume_and_unlock();
return ret;
@ -1813,7 +1816,6 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
if (pr->flags.power) {
#ifdef CONFIG_CPU_IDLE
acpi_processor_setup_cpuidle(pr);
pr->power.dev.cpu = pr->id;
if (cpuidle_register_device(&pr->power.dev))
return -EIO;
#endif
@ -1850,8 +1852,7 @@ int acpi_processor_power_exit(struct acpi_processor *pr,
return 0;
#ifdef CONFIG_CPU_IDLE
if (pr->flags.power)
cpuidle_unregister_device(&pr->power.dev);
cpuidle_unregister_device(&pr->power.dev);
#endif
pr->flags.power_setup_done = 0;