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PM / runtime: add note about re-calling in during device probe()

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The sh_eth driver has come up with an issue where the runtime_pm
code suspends it during the probe() method due to the network
device registration re-calling into the driver.

Add a note about this into the documentation.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Ben Dooks 2015-04-17 01:14:15 +01:00 committed by Rafael J. Wysocki
parent 030bbdbf4c
commit f6a2fbb903
1 changed files with 6 additions and 0 deletions
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6
Documentation/power/runtime_pm.txt
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@ -556,6 +556,12 @@ helper functions described in Section 4. In that case, pm_runtime_resume()
should be used. Of course, for this purpose the device's runtime PM has to be should be used. Of course, for this purpose the device's runtime PM has to be
enabled earlier by calling pm_runtime_enable(). enabled earlier by calling pm_runtime_enable().
Note, if the device may execute pm_runtime calls during the probe (such as
if it is registers with a subsystem that may call back in) then the
pm_runtime_get_sync() call paired with a pm_runtime_put() call will be
appropriate to ensure that the device is not put back to sleep during the
probe. This can happen with systems such as the network device layer.
It may be desirable to suspend the device once ->probe() has finished. It may be desirable to suspend the device once ->probe() has finished.
Therefore the driver core uses the asyncronous pm_request_idle() to submit a Therefore the driver core uses the asyncronous pm_request_idle() to submit a
request to execute the subsystem-level idle callback for the device at that request to execute the subsystem-level idle callback for the device at that