On Sun, Jun 18, 2017 at 06:50:27AM +1000, Benjamin Herrenschmidt wrote: > What is your rationale here ? (I have missed patch 0 it seems). Less code duplication, more modular dma_map_ops insteance. > dma_supported() was supposed to be pretty much a "const" function > simply informing whether a given setup is possible. Having it perform > an actual switch of ops seems to be pushing it... dma_supported() is already gone from the public DMA API as it doesn't make sense to be called separately from set_dma_mask. It will be entirely gone in the next series after this one. > What if a driver wants to test various dma masks and then pick one ? > > Where does the API documents that if a driver calls dma_supported() it > then *must* set the corresponding mask and use that ? Where is the API document for _any_ of the dma routines? (A: work in progress by me, but I need to clean up the mess of arch hooks before it can make any sense) > I don't like a function that is a "boolean query" like this one to have > such a major side effect. > > >From an API standpoint, dma_set_mask() is when the mask is established, > and thus when the ops switch should happen. And that's exactly what happens at the driver API level. It just turns out the dma_capable method is they way better place to actually implement it, as the ->set_dma_mask method requires lots of code duplication while not offering any actual benefit over ->dma_capable. And because of that it's gone after this series. In theory we could rename ->dma_capable now, but it would require a _lot_ of churn. Give me another merge window or two and we should be down to be about 2 handful of dma_map_ops instance, at which point we could do all this gratious renaming a lot more easily :)
