2013/3/23 Chris Vine <chris@xxxxxxxxxxxxxxxxxxxxx>: > On Sat, 23 Mar 2013 11:35:17 +0100 > Michael Büsch <m@xxxxxxx> wrote: >> 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... > > For what it is worth, this happens to me on both home compiled and > distributor kernels (ubuntu and slackware): in fact, any 32-bit kernel > that I have tried it on. > > And it does not happen with the wl driver on the same kernels. So if > this is right, the wl driver must be doing something that the b43 driver > does not with respect to alignment: and you might well be right about > that. Could you try changing B43_DMA32_RINGMEMSIZE from 4096 to 8192 in dma.h? -- Rafał -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
