Messages in this thread | | | Subject | Re: [PATCH 5/6] dma-mapping: support fsl-mc bus | From | Robin Murphy <> | Date | Mon, 5 Mar 2018 18:51:56 +0000 |
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On 05/03/18 18:39, Christoph Hellwig wrote: > On Mon, Mar 05, 2018 at 03:48:32PM +0000, Robin Murphy wrote: >> Unfortunately for us, fsl-mc is conceptually rather like PCI in that it's >> software-discoverable and the only thing described in DT is the bus "host", >> thus we need the same sort of thing as for PCI to map from the child >> devices back to the bus root in order to find the appropriate firmware >> node. Worse than PCI, though, we wouldn't even have the option of >> describing child devices statically in firmware at all, since it's actually >> one of these runtime-configurable "build your own network accelerator" >> hardware pools where userspace gets to create and destroy "devices" as it >> likes. > > I really hate the PCI special case just as much. Maybe we just > need a dma_configure method on the bus, and move PCI as well as fsl-mc > to it.
Hmm, on reflection, 100% ack to that idea. It would neatly supersede bus->force_dma *and* mean that we don't have to effectively pull pci.h into everything, which I've never liked. In hindsight dma_configure() does feel like it's grown into this odd choke point where we munge everything in just for it to awkwardly unpick things again.
Robin.
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