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    Subject[PATCH 1/1] driver core: disable device's runtime pm during shutdown
    Date
    There may be an issue when the user issue "reboot/shutdown" command, then
    the device has shut down its hardware, after that, this runtime-pm featured
    device's driver will probably be scheduled to do its suspend routine,
    and at its suspend routine, it may access hardware, but the device has
    already shutdown physically, then the system hang may be occurred.

    I ran out this issue using an auto-suspend supported USB devices, like
    3G modem, keyboard. The usb runtime suspend routine may be scheduled
    after the usb controller has been shut down, and the usb runtime suspend
    routine will try to suspend its roothub(controller), it will access
    register, then the system hang occurs as the controller is shutdown.
    Signed-off-by: Peter Chen <peter.chen@freescale.com>
    ---
    drivers/base/core.c | 3 +++
    1 files changed, 3 insertions(+), 0 deletions(-)

    diff --git a/drivers/base/core.c b/drivers/base/core.c
    index bc8729d..78445f4 100644
    --- a/drivers/base/core.c
    +++ b/drivers/base/core.c
    @@ -22,6 +22,7 @@
    #include <linux/kallsyms.h>
    #include <linux/mutex.h>
    #include <linux/async.h>
    +#include <linux/pm_runtime.h>

    #include "base.h"
    #include "power/power.h"
    @@ -1742,6 +1743,8 @@ void device_shutdown(void)
    */
    list_del_init(&dev->kobj.entry);
    spin_unlock(&devices_kset->list_lock);
    + /* Disable all device's runtime power management */
    + pm_runtime_disable(dev);

    if (dev->bus && dev->bus->shutdown) {
    dev_dbg(dev, "shutdown\n");
    --
    1.7.1



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