[PATCH] B43: Handle DMA RX descriptor underrun

[Rafał Miłecki]

2013/4/23 Thommy Jakobsson <thommyj at gmail.com>:
> Add handling of rx descriptor underflow. This fixes a fault that could
> happen on slow machines, where data is received faster than the CPU can
> handle. In such a case the device will use up all rx descriptors and
> refuse to send any more data before confirming that it is ok. This
> patch enables necessary interrupt to discover such a situation and will
> handle them by dropping everything in the ring buffer.

Thommy: does it mean firmware actually ignores what we write to the
B43_DMA64_RXINDEX (recently renamed to the B43_DMA64_RXSTOPINDEX)? Is
our set_current_rxslot and op64_set_current_rxslot (same for 32bit
version) useless in this situation?

Could this be a off-by-one issue? Maybe we're writing a value too low
by a one and firmware believes the whole ring is empty while it's
full?

I think we may want turning this interrupt anyway, but I wonder if
there is another issue we just hide a bit better.

-- 
Rafał