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| author | Otavio Salvador <otavio@ossystems.com.br> | 2020-05-20 08:43:03 -0300 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-05-20 08:43:03 -0300 |
| commit | 1279cd128bba968ebe0a2df7f7ae38bae90250ef (patch) | |
| tree | df6b1a190760f51465122ca4c13492d5ac5984c6 /Documentation/usb/power-management.txt | |
| parent | 0a8ab17689e628c84a666195bfc6ab85d11cf057 (diff) | |
| parent | 2ae782ca839e0ee07de37122ddea362adff2e975 (diff) | |
Merge pull request #76 from toradex/4.9-2.3.x-imx
4.9 2.3.x imx
Diffstat (limited to 'Documentation/usb/power-management.txt')
| -rw-r--r-- | Documentation/usb/power-management.txt | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt index 0a94ffe17ab6..b13e031beaa6 100644 --- a/Documentation/usb/power-management.txt +++ b/Documentation/usb/power-management.txt @@ -365,11 +365,15 @@ autosuspend the interface's device. When the usage counter is = 0 then the interface is considered to be idle, and the kernel may autosuspend the device. -Drivers need not be concerned about balancing changes to the usage -counter; the USB core will undo any remaining "get"s when a driver -is unbound from its interface. As a corollary, drivers must not call -any of the usb_autopm_* functions after their disconnect() routine has -returned. +Drivers must be careful to balance their overall changes to the usage +counter. Unbalanced "get"s will remain in effect when a driver is +unbound from its interface, preventing the device from going into +runtime suspend should the interface be bound to a driver again. On +the other hand, drivers are allowed to achieve this balance by calling +the ``usb_autopm_*`` functions even after their ``disconnect`` routine +has returned -- say from within a work-queue routine -- provided they +retain an active reference to the interface (via ``usb_get_intf`` and +``usb_put_intf``). Drivers using the async routines are responsible for their own synchronization and mutual exclusion. |