spurious (and fatal) interrupt errors.
One user reported seeing this:
Apr 22 18:04:24 ceres kernel: ar5416GetPendingInterrupts: fatal error,
ISR_RAC 0x0 SYNC_CAUSE 0x2000
SYNC_CAUSE of 0x2000 is AR_INTR_SYNC_LOCAL_TIMEOUT which is a bus timeout;
this shouldn't cause HAL_INT_FATAL to be set.
After checking out ath9k, ath9k_ar9002_hw_get_isr() clears (*masked)
before continuing, regardless of whether any bits in the ISR registers
are set. So if AR_INTR_SYNC_CAUSE is set to something that isn't
treated as fatal, and AR_ISR isn't read or is read and is 0, then
(*masked) wouldn't be cleared. Thus any of the existing bits set
that were passed in would be preserved in the output.
The caller in if_ath - ath_intr() - wasn't setting the masked value
to 0 before calling ath_hal_getisr(), so anything that was present
in that uninitialised variable would be preserved in the case above
of AR_ISR=0, AR_INTR_SYNC_CAUSE != 0; and if the HAL_INT_FATAL bit
was set, a fatal condition would be interpreted and the chip was
reset.
This patch does the following:
* ath_intr() - set masked to 0 before calling ath_hal_getisr();
* ar5416GetPendingInterrupts() - clear (*masked) before processing
continues; so if the interrupt source is AR_INTR_SYNC_CAUSE
and it isn't fatal, the hardware isn't reset via returning
HAL_INT_FATAL.
This doesn't fix any underlying errors which trigger
AR_INTR_SYNC_LOCAL_TIMEOUT - which is a bus timeout of some
sort - so that likely should be further investigated.
6f5fe81e02