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    Subject[PATCH 8/13] ACPI / PM: Add function for updating device power state consistently
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    Add function acpi_bus_update_power() for reading the actual power
    state of an ACPI device and updating its device->power.state field
    in such a way that its power resources' reference counters will
    remain consistent with that field.

    For this purpose introduce __acpi_bus_set_power() setting the
    power state of an ACPI device without updating its
    device->power.state field and make acpi_bus_set_power() and
    acpi_bus_update_power() use it (acpi_bus_set_power() retains the
    current behavior for now).

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    ---
    drivers/acpi/bus.c | 90 ++++++++++++++++++++++++++++++++----------------
    include/acpi/acpi_bus.h | 1
    2 files changed, 62 insertions(+), 29 deletions(-)

    Index: linux-2.6/drivers/acpi/bus.c
    ===================================================================
    --- linux-2.6.orig/drivers/acpi/bus.c
    +++ linux-2.6/drivers/acpi/bus.c
    @@ -255,44 +255,17 @@ int acpi_bus_get_power(acpi_handle handl
    EXPORT_SYMBOL(acpi_bus_get_power);


    -int acpi_bus_set_power(acpi_handle handle, int state)
    +static int __acpi_bus_set_power(struct acpi_device *device, int state)
    {
    int result = 0;
    acpi_status status = AE_OK;
    - struct acpi_device *device = NULL;
    char object_name[5] = { '_', 'P', 'S', '0' + state, '\0' };

    -
    - result = acpi_bus_get_device(handle, &device);
    - if (result)
    - return result;
    -
    - if ((state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
    + if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
    return -EINVAL;

    /* Make sure this is a valid target state */

    - if (!device->flags.power_manageable) {
    - ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device `[%s]' is not power manageable\n",
    - kobject_name(&device->dev.kobj)));
    - return -ENODEV;
    - }
    - /*
    - * Get device's current 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));
    @@ -362,6 +335,42 @@ int acpi_bus_set_power(acpi_handle handl
    return result;
    }

    +
    +int acpi_bus_set_power(acpi_handle handle, int state)
    +{
    + struct acpi_device *device;
    + int result;
    +
    + result = acpi_bus_get_device(handle, &device);
    + if (result)
    + return result;
    +
    + if (!device->flags.power_manageable) {
    + ACPI_DEBUG_PRINT((ACPI_DB_INFO,
    + "Device [%s] is not power manageable\n",
    + dev_name(&device->dev)));
    + return -ENODEV;
    + }
    +
    + /*
    + * Get device's current 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, &device->power.state);
    + }
    +
    + return __acpi_bus_set_power(device, state);
    +}
    EXPORT_SYMBOL(acpi_bus_set_power);


    @@ -389,6 +398,29 @@ int acpi_bus_init_power(struct acpi_devi
    }


    +int acpi_bus_update_power(acpi_handle handle, int *state_p)
    +{
    + struct acpi_device *device;
    + int state;
    + int result;
    +
    + result = acpi_bus_get_device(handle, &device);
    + if (result)
    + return result;
    +
    + result = __acpi_bus_get_power(device, &state);
    + if (result)
    + return result;
    +
    + result = __acpi_bus_set_power(device, state);
    + if (!result && state_p)
    + *state_p = state;
    +
    + return result;
    +}
    +EXPORT_SYMBOL_GPL(acpi_bus_update_power);
    +
    +
    bool acpi_bus_power_manageable(acpi_handle handle)
    {
    struct acpi_device *device;
    Index: linux-2.6/include/acpi/acpi_bus.h
    ===================================================================
    --- linux-2.6.orig/include/acpi/acpi_bus.h
    +++ linux-2.6/include/acpi/acpi_bus.h
    @@ -330,6 +330,7 @@ acpi_status acpi_bus_get_status_handle(a
    int acpi_bus_get_status(struct acpi_device *device);
    int acpi_bus_get_power(acpi_handle handle, int *state);
    int acpi_bus_set_power(acpi_handle handle, int state);
    +int acpi_bus_update_power(acpi_handle handle, int *state_p);
    bool acpi_bus_power_manageable(acpi_handle handle);
    bool acpi_bus_can_wakeup(acpi_handle handle);
    #ifdef CONFIG_ACPI_PROC_EVENT


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