On 05/05/2015 03:57 PM, Joe Perches wrote: > On Tue, 2015-05-05 at 11:25 +0200, Michal Simek wrote: >> From: Peter Crosthwaite <peter.crosthwa...@xilinx.com> >> >> The AXI-DMA rx-delay interrupt can sometimes be triggered >> when there are 0 outstanding packets received. This is due >> to the fact that the receive function will greedily consume >> as many packets as possible on interrupt. So if two packets >> (with a very particular timing) arrive in succession they >> will each cause the rx-delay interrupt, but the first interrupt >> will consume both packets. >> This means the second interrupt is a 0 packet receive. >> >> This is mostly OK, except that the tail pointer register is >> updated unconditionally on receive. Currently the tail pointer >> is always set to the current bd-ring descriptor under >> the assumption that the hardware has moved onto the next >> descriptor. What this means for length 0 recv is the current >> descriptor that the hardware is potentially yet to use will >> be marked as the tail. This causes the hardware to think >> its run out of descriptors deadlocking the whole rx path. >> >> Fixed by updating the tail pointer to the most recent >> successfully consumed descriptor. > > I think some of this would be good to have as comments > in the code instead of just in the changelog.
Is it really needed? If yes, no problem to add it but git blame can point you to that. Thanks, Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
