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Diffstat (limited to 'Documentation/rfkill.txt')
| -rw-r--r-- | Documentation/rfkill.txt | 49 |
1 files changed, 45 insertions, 4 deletions
diff --git a/Documentation/rfkill.txt b/Documentation/rfkill.txt index 0843ed0163a5..b65f0799df48 100644 --- a/Documentation/rfkill.txt +++ b/Documentation/rfkill.txt @@ -341,6 +341,8 @@ key that does nothing by itself, as well as any hot key that is type-specific 3.1 Guidelines for wireless device drivers ------------------------------------------ +(in this text, rfkill->foo means the foo field of struct rfkill). + 1. Each independent transmitter in a wireless device (usually there is only one transmitter per device) should have a SINGLE rfkill class attached to it. @@ -363,6 +365,33 @@ This rule exists because users of the rfkill subsystem expect to get (and set, when possible) the overall transmitter rfkill state, not of a particular rfkill line. +5. The wireless device driver MUST NOT leave the transmitter enabled during +suspend and hibernation unless: + + 5.1. The transmitter has to be enabled for some sort of functionality + like wake-on-wireless-packet or autonomous packed forwarding in a mesh + network, and that functionality is enabled for this suspend/hibernation + cycle. + +AND + + 5.2. The device was not on a user-requested BLOCKED state before + the suspend (i.e. the driver must NOT unblock a device, not even + to support wake-on-wireless-packet or remain in the mesh). + +In other words, there is absolutely no allowed scenario where a driver can +automatically take action to unblock a rfkill controller (obviously, this deals +with scenarios where soft-blocking or both soft and hard blocking is happening. +Scenarios where hardware rfkill lines are the only ones blocking the +transmitter are outside of this rule, since the wireless device driver does not +control its input hardware rfkill lines in the first place). + +6. During resume, rfkill will try to restore its previous state. + +7. After a rfkill class is suspended, it will *not* call rfkill->toggle_radio +until it is resumed. + + Example of a WLAN wireless driver connected to the rfkill subsystem: -------------------------------------------------------------------- @@ -390,9 +419,10 @@ 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 +452,24 @@ 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. |