On Sun, 2017-06-18 at 00:13 -0700, Christoph Hellwig wrote: > 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.
Ah ok, in that case it makes much more sense, we can rename it then. > > 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) Heh fair enough. > > 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 :) Sure, I get it now, as long as it's not publicly exposed to drivers we are fine. Cheers, Ben.
