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    Subject[PATCH v4] PM: sleep: core: Avoid setting power.must_resume to false
    Date
    There are variables(power.may_skip_resume and dev->power.must_resume)
    and DPM_FLAG_MAY_SKIP_RESUME flags to control the resume of devices after
    a system wide suspend transition.

    Setting the DPM_FLAG_MAY_SKIP_RESUME flag means that the driver allows
    its "noirq" and "early" resume callbacks to be skipped if the device
    can be left in suspend after a system-wide transition into the working
    state. PM core determines that the driver's "noirq" and "early" resume
    callbacks should be skipped or not with dev_pm_skip_resume() function by
    checking power.may_skip_resume variable.

    power.must_resume variable is getting set to false in __device_suspend()
    function without checking device's DPM_FLAG_MAY_SKIP_RESUME settings.
    In problematic scenario, where all the devices in the suspend_late
    stage are successful and some device can fail to suspend in
    suspend_noirq phase. So some devices successfully suspended in suspend_late
    stage are not getting chance to execute __device_suspend_noirq()
    to set dev->power.must_resume variable to true and not getting
    resumed in early_resume phase.

    Add a check for device's DPM_FLAG_MAY_SKIP_RESUME flag before
    setting power.must_resume variable in __device_suspend function.

    Fixes: 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the resume phase")
    Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
    ---
    V3 -> V4: Remove dev->power.usage_count variable check
    V2 -> V3: Format issues patch posting
    V1 -> V2: Fixed indentation and commit text to include scenario
    drivers/base/power/main.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
    index d568772..50e8ea3 100644
    --- a/drivers/base/power/main.c
    +++ b/drivers/base/power/main.c
    @@ -1642,7 +1642,10 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
    }

    dev->power.may_skip_resume = true;
    - dev->power.must_resume = false;
    + if (dev_pm_test_driver_flags(dev, DPM_FLAG_MAY_SKIP_RESUME))
    + dev->power.must_resume = false;
    + else
    + dev->power.must_resume = true;

    dpm_watchdog_set(&wd, dev);
    device_lock(dev);
    --
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
    a Linux Foundation Collaborative Project
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