On Sat, 23 Mar 2013 00:27:30 +0100 Rafał Miłecki <zajec5@xxxxxxxxx> wrote: > Today I've plugged my 14e4:4315 and (unfortunately?) it's working > pretty well. I hoped to reproduce some problems but failed to do so. I > was transmitting for an hour with average speed 11MiB/s and didn't > notice any DMA issues. > > I was using iperf with interval of 60 seconds and only 3 results > showed some problems (8.5MiB/s, 2.5MiB/s, 4.5MiB/s). No disconnections > however and no DMA errors. I just got "Group rekeying completed..." in > wpa_supplicant. > > So as I can't reproduce this, I can't find any other fix for this > issue, and there's no reason to stop this workaround. I'll just apply > it and test over weekend to check for any regressions, but they are > highly unlikely. I don't really believe in this being a firmware bug. Some b43 DMA engines (all?) have some alignment and page-boundary-crossing constraints. I would rather guess that on some kernels with some options turned on, alignment and/or boundary constraints are violated every now and then. (and thus the packet never reaches the firmware). I don't remember the details, though. Too long since I worked on that. But a few sanity checks could probably be added to the code to check this hypothesis. Does the failing kernel/machine have any special things w.r.t. memory? Like iommu, hugepages, whetever... -- Michael
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