> I had the same thought, but notice that you also need to update > ring->current_slot in b43_dma_rx_discard. > > When ring->current_slot update is missing (as in your original > patch), you will introduce the same problem I hit by removing > ops->set_current_rxslot(ring, slot) from b43_dma_rx (disabling > RX underflow detection). Basically we break assumptions about > ownership of descriptors (which descriptors are exclusively used > by host and which can be written by DMA processor). So next time > b43_dma_rx is called it may process descriptors that are updated > by DMA processor at the same time (race condition). Why would I update ring->current_slot? That should point where we are in the ring from the drivers perspective. Since that i always updated together with the rx index (set_current_rxslot) it will always be the same as the current index in hw (get_current_rxslot) in the b43_rx_discard. That is also where it should be.
It is true that I'll introduce a possibility for ownership problem with the original patch, but that will only last until the next time b43_dma_rx is called. Which is just after the b43_dma_rx_discard has exited since you always will get a rx interrupt at the same time as the underflow interrupt. This is also the case at each startup since rx index is initilised to the same thing as I used. I have tested the index-1 that me and michael talked about, from the initial test is working just fine. Im running with only 8 rxslots to try to find any corner cases, so I see a lot of traffic drops though. This would also fix the ownership problem. BTW, it is confusing that set and get current_rxslot doesn't updated and read the same register. About the FIFO errors I haven't looked at those at all. I did get some other errors when I pumped data at link speed into my router, but that was for TX. //Thommy _______________________________________________ b43-dev mailing list b43-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/b43-dev
