[PATCH] b43: use rx desc underrun interrupt

[Thommy Jakobsson]

On Sat, 20 Apr 2013, Michael Büsch wrote:

> On Sat, 20 Apr 2013 16:14:09 +0200 (CEST)
> Thommy <thommyj at gmail.com> wrote:
> 
> > +void b43_dma_rx_discard(struct b43_dmaring *ring)
> > +{
> > +	B43_WARN_ON(ring->tx);
> > +
> > +	/* Device has filled all buffers, drop all packets in buffers
> > +	* and let TCP decrease speed.
> > +	* Set index to one desc after the last one
> > +	* so the device will see all slots as free again
> > +	*/
> > +	/*
> > +	*TODO: How to increase rx_drop in mac80211?
> > +	*/
> > +	b43_dma_write(ring, B43_DMA32_RXINDEX, ring->nr_slots *
> > +			sizeof(struct b43_dmadesc32));
> > +}
> 
> You need to check whether this is a 32bit or 64bit DMA engine and
> write to B43_DMA32_RXINDEX or B43_DMA64_RXINDEX.
> You could simply use the ring->ops->set_current_rxslot() dmaop for that.
>
Good point, I'll fix that

> And I think you need to set ring->current_slot to the value of ring->ops->get_current_slot().
> Not 100% sure, though, since it is years since I worked on that code.
> 
Is that really needed? They should already be the same since the device 
has thrown the underflow interrupt, or do I miss some race condition?

//thommy