Messages in this thread | | | Date | Wed, 31 Oct 2018 14:24:13 +0000 (GMT) | From | "Maciej W. Rozycki" <> | Subject | Re: [PATCH 4/6] dma-mapping: merge direct and noncoherent ops |
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Hi Christoph,
On Fri, 14 Sep 2018, Christoph Hellwig wrote:
> All the cache maintainance is already stubbed out when not enabled, > but merging the two allows us to nicely handle the case where > cache maintainance is required for some devices, but not others.
FYI, you commit bc3ec75de545 ("dma-mapping: merge direct and noncoherent ops") has caused:
fddi0: DMA command request failed! fddi0: Adapter open failed!
with the `defxx' driver on my R4400SC TURBOchannel DECstation (but not the R3400 one) and consequently the interface does not work anymore. Both are non-coherent cache systems, however the R3400 implements the write-through policy while the policy of the R4400SC is write-back (it also has 1MiB of secondary cache), which I suspect is the reason of the difference.
I'll be experimenting with this commit to figure out what the real cause is, but it'll take a while as my resources are limited, so I'm sending this early heads-up in case you or someone else has an idea what might be going wrong here.
Maciej
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