Re: [PATCH v4] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller

From: Francois Romieu
Date: Sat Oct 31 2015 - 14:08:45 EST

MÃns RullgÃrd <mans@xxxxxxxxx> :
> Francois Romieu <romieu@xxxxxxxxxxxxx> writes:
> > It looks like it receives, then tries to allocate new resources. If so
> > it may deplete the ring and you should instead consider allocating new
> > resources first, then receive data if alloc + map suceeded.
> The hardware receives a frame and stores it in the provided DMA buffer,
> then raises an interrupt and moves on to the next buffer. When a buffer
> is handed over to the network stack, a new one has to take its place in
> the DMA queue. I'm not sure how you're suggesting this be done
> differently.

- The hardware raises an interrupt and moves on to the next packet
- The driver allocates a new buffer - call it Bob - and maps it.
- If it succeeds
- The driver unmaps the received packet
- The driver hands the received packet to the network stack
- The driver hands Bob to the hardware
- It it fails
- The driver updates the dropped packet stats
- The driver recycles the received - yet non-unmapped - packet to the

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