> From: Robin Murphy [mailto:robin.mur...@arm.com] > Sent: Tuesday, March 06, 2018 0:22 > > 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.
+1 to the idea. Sorry for asking a trivial question - looking into dma_configure() I see that PCI is used in the start and the end of the API. In the end part pci_put_host_bridge_device() is called. So are two bus callbacks something like 'dma_config_start' & 'dma_config_end' will be required where the former one will return "dma_dev"? Regards, Nipun _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
