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| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | 2008-07-21 21:18:17 -0300 |
|---|---|---|
| committer | John W. Linville <linville@tuxdriver.com> | 2008-07-29 16:36:32 -0400 |
| commit | 2fd9b2212e25e6411b6f309707f4e2683d164250 (patch) | |
| tree | b886e6d11d3478f86ac7e270ef1dfc7fe02e7128 /Documentation | |
| parent | 734b5aa911dc65f4563048f069dfc631c9aa7de7 (diff) | |
| download | linux-2fd9b2212e25e6411b6f309707f4e2683d164250.tar.gz linux-2fd9b2212e25e6411b6f309707f4e2683d164250.tar.bz2 linux-2fd9b2212e25e6411b6f309707f4e2683d164250.zip | |
rfkill: document rfkill_force_state as required (v2)
While the rfkill class does work with just get_state(), it doesn't work
well on devices that are subject to external events that cause rfkill state
changes.
Document that rfkill_force_state() is required in those cases.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/rfkill.txt | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/Documentation/rfkill.txt b/Documentation/rfkill.txt index 0843ed0163a5..28b6ec87c642 100644 --- a/Documentation/rfkill.txt +++ b/Documentation/rfkill.txt @@ -390,9 +390,10 @@ rfkill lines are inactive, it must return RFKILL_STATE_SOFT_BLOCKED if its soft rfkill input line is active. Only if none of the rfkill input lines are active, will it return RFKILL_STATE_UNBLOCKED. -If it doesn't implement the get_state() hook, it must make sure that its calls -to rfkill_force_state() are enough to keep the status always up-to-date, and it -must do a rfkill_force_state() on resume from sleep. +Since the device has a hardware rfkill line, it IS subject to state changes +external to rfkill. Therefore, the driver must make sure that it calls +rfkill_force_state() to keep the status always up-to-date, and it must do a +rfkill_force_state() on resume from sleep. Every time the driver gets a notification from the card that one of its rfkill lines changed state (polling might be needed on badly designed cards that don't @@ -422,13 +423,24 @@ of the hardware is unknown), or read-write (where the hardware can be queried about its current state). The rfkill class will call the get_state hook of a device every time it needs -to know the *real* current state of the hardware. This can happen often. +to know the *real* current state of the hardware. This can happen often, but +it does not do any polling, so it is not enough on hardware that is subject +to state changes outside of the rfkill subsystem. + +Therefore, calling rfkill_force_state() when a state change happens is +mandatory when the device has a hardware rfkill line, or when something else +like the firmware could cause its state to be changed without going through the +rfkill class. Some hardware provides events when its status changes. In these cases, it is best for the driver to not provide a get_state hook, and instead register the rfkill class *already* with the correct status, and keep it updated using rfkill_force_state() when it gets an event from the hardware. +rfkill_force_state() must be used on the device resume handlers to update the +rfkill status, should there be any chance of the device status changing during +the sleep. + There is no provision for a statically-allocated rfkill struct. You must use rfkill_allocate() to allocate one. |