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    SubjectRe: [RFT/RFC][PATCH] driver core: Fix PM-runtime for links added during consumer probe
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    On 18/02/2019 22:08, Rafael J. Wysocki wrote:
    > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >
    > Commit 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage
    > counter imbalance") introduced a regression that causes suppliers
    > to be suspended prematurely for device links added during consumer
    > driver probe if the initial PM-runtime status of the consumer is
    > "suspended" and the consumer is resumed after adding the link and
    > before pm_runtime_put_suppliers() is called. In that case,
    > pm_runtime_put_suppliers() will drop the rpm_active refcount for
    > the link by one and (since rpm_active is equal to two after the
    > preceding consumer resume) the supplier's PM-runtime usage counter
    > will be decremented, which may cause the supplier to suspend even
    > though the consumer's PM-runtime status is "active".
    >
    > For this reason, partially revert commit 4c06c4e6cf63 as the problem
    > it tried to fix needs to be addressed somewhat differently, and
    > change pm_runtime_get_suppliers() and pm_runtime_put_suppliers() so
    > that the latter only drops rpm_active references acquired by the
    > former. [This requires adding a new field to struct device_link,
    > but I coulnd't find a cleaner way to address the issue that would
    > work in all cases.]
    >
    > Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
    > Reported-by: Jon Hunter <jonathanh@nvidia.com>
    > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > ---
    >
    > On top of driver-core/driver-core-next.
    >
    > Jon, Ulf, please test!

    Thanks Rafael this works for me!

    Tested-by: Jon Hunter <jonathanh@nvidia.com>

    Cheers
    Jon

    --
    nvpublic

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