iwl3945: fix rfkill switch
(Not needed upstream, due to the major rewrite in 2.6.31)
Due to rfkill and iwlwifi mishmash of SW / HW killswitch representation,
we have race conditions which make unable turn wifi radio on, after enable
and disable again killswitch. I can observe this problem on my laptop
with iwl3945 device.
In rfkill core HW switch and SW switch are separate 'states'. Device can
be only in one of 3 states: RFKILL_STATE_SOFT_BLOCKED, RFKILL_STATE_UNBLOCKED,
RFKILL_STATE_HARD_BLOCKED. Whereas in iwlwifi driver we have separate bits
STATUS_RF_KILL_HW and STATUS_RF_KILL_SW for HW and SW switches - radio can be
turned on, only if both bits are cleared.
In this particular race conditions, radio can not be turned on if in driver
STATUS_RF_KILL_SW bit is set, and rfkill core is in state
RFKILL_STATE_HARD_BLOCKED, because rfkill core is unable to call
rfkill->toggle_radio(). This situation can be entered in case:
- killswitch is turned on
- rfkill core 'see' button change first and move to RFKILL_STATE_SOFT_BLOCKED
also call ->toggle_radio() and STATE_RF_KILL_SW in driver is set
- iwl3945 get info about button from hardware to set STATUS_RF_KILL_HW bit and
force rfkill to move to RFKILL_STATE_HARD_BLOCKED
- killsiwtch is turend off
- driver clear STATUS_RF_KILL_HW
- rfkill core is unable to clear STATUS_RF_KILL_SW in driver
Additionally call to rfkill_epo() when STATUS_RF_KILL_HW in driver is set
cause move to the same situation.
In 2.6.31 this problem is fixed due to _total_ rewrite of rfkill subsystem.
This is a quite small fix for 2.6.30.x in iwlwifi driver. We are changing
internal rfkill state to always have below relations true:
STATUS_RF_KILL_HW=1 STATUS_RF_KILL_SW=1 <-> RFKILL_STATUS_SOFT_BLOCKED
STATUS_RF_KILL_HW=0 STATUS_RF_KILL_SW=1 <-> RFKILL_STATUS_SOFT_BLOCKED
STATUS_RF_KILL_HW=1 STATUS_RF_KILL_SW=0 <-> RFKILL_STATUS_HARD_BLOCKED
STATUS_RF_KILL_HW=0 STATUS_RF_KILL_SW=0 <-> RFKILL_STATUS_UNBLOCKED
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: John W. Linville <linville@tuxdriver.com>