4 files changed, 53 insertions, 12 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 44d1bd142edf..99cf83fd6947 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -251,6 +251,14 @@ and is between 256 and 4096 characters. It is defined in the file
                         Warning: Many of these options can produce a lot of
                         output and make your system unusable. Be very careful.
 
+        acpi.power_nocheck=     [HW,ACPI]
+                        Format: 1/0 enable/disable the check of power state.
+                        On some bogus BIOS the _PSC object/_STA object of
+                        power resource can't return the correct device power
+                        state. In such case it is unneccessary to check its
+                        power state again in power transition.
+                        1 : disable the power state check
+
         acpi_pm_good    [X86-32,X86-64]
                         Override the pmtimer bug detection: force the kernel
                         to assume that this machine's pmtimer latches its value
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index ccae305ee55d..91bdeb3b081e 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -223,7 +223,19 @@ int acpi_bus_set_power(acpi_handle handle, int state)
         /*
          * Get device's current power state
          */
-        acpi_bus_get_power(device->handle, &device->power.state);
+        if (!acpi_power_nocheck) {
+                /*
+                 * Maybe the incorrect power state is returned on the bogus
+                 * bios, which is different with the real power state.
+                 * For example: the bios returns D0 state and the real power
+                 * state is D3. OS expects to set the device to D0 state. In
+                 * such case if OS uses the power state returned by the BIOS,
+                 * the device can't be transisted to the correct power state.
+                 * So if the acpi_power_nocheck is set, it is unnecessary to
+                 * get the power state by calling acpi_bus_get_power.
+                 */
+                acpi_bus_get_power(device->handle, &device->power.state);
+        }
         if ((state == device->power.state) && !device->flags.force_power_state) {
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device is already at D%d\n",
                                   state));
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index e7bab75075a9..7ff7349c0c52 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -54,6 +54,14 @@ ACPI_MODULE_NAME("power");
 #define ACPI_POWER_RESOURCE_STATE_OFF   0x00
 #define ACPI_POWER_RESOURCE_STATE_ON    0x01
 #define ACPI_POWER_RESOURCE_STATE_UNKNOWN 0xFF
+
+#ifdef MODULE_PARAM_PREFIX
+#undef MODULE_PARAM_PREFIX
+#endif
+#define MODULE_PARAM_PREFIX "acpi."
+int acpi_power_nocheck;
+module_param_named(power_nocheck, acpi_power_nocheck, bool, 000);
+
 static int acpi_power_add(struct acpi_device *device);
 static int acpi_power_remove(struct acpi_device *device, int type);
 static int acpi_power_resume(struct acpi_device *device);
@@ -228,12 +236,18 @@ static int acpi_power_on(acpi_handle handle, struct acpi_device *dev)
         if (ACPI_FAILURE(status))
                 return -ENODEV;
 
-        result = acpi_power_get_state(resource->device->handle, &state);
-        if (result)
-                return result;
-        if (state != ACPI_POWER_RESOURCE_STATE_ON)
-                return -ENOEXEC;
-
+        if (!acpi_power_nocheck) {
+                /*
+                 * If acpi_power_nocheck is set, it is unnecessary to check
+                 * the power state after power transition.
+                 */
+                result = acpi_power_get_state(resource->device->handle,
+                                &state);
+                if (result)
+                        return result;
+                if (state != ACPI_POWER_RESOURCE_STATE_ON)
+                        return -ENOEXEC;
+        }
         /* Update the power resource's _device_ power state */
         resource->device->power.state = ACPI_STATE_D0;
 
@@ -279,11 +293,17 @@ static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev)
         if (ACPI_FAILURE(status))
                 return -ENODEV;
 
-        result = acpi_power_get_state(handle, &state);
-        if (result)
-                return result;
-        if (state != ACPI_POWER_RESOURCE_STATE_OFF)
-                return -ENOEXEC;
+        if (!acpi_power_nocheck) {
+                /*
+                 * If acpi_power_nocheck is set, it is unnecessary to check
+                 * the power state after power transition.
+                 */
+                result = acpi_power_get_state(handle, &state);
+                if (result)
+                        return result;
+                if (state != ACPI_POWER_RESOURCE_STATE_OFF)
+                        return -ENOEXEC;
+        }
 
         /* Update the power resource's _device_ power state */
         resource->device->power.state = ACPI_STATE_D3;
diff --git a/include/acpi/acpi_drivers.h b/include/acpi/acpi_drivers.h
index e5f38e5ce86f..efbaa271ee11 100644
--- a/include/acpi/acpi_drivers.h
+++ b/include/acpi/acpi_drivers.h
@@ -93,6 +93,7 @@ int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state);
 int acpi_disable_wakeup_device_power(struct acpi_device *dev);
 int acpi_power_get_inferred_state(struct acpi_device *device);
 int acpi_power_transition(struct acpi_device *device, int state);
+extern int acpi_power_nocheck;
 #endif
 
 /* --------------------------------------------------------------------------