Messages in this thread | | | Date | Fri, 09 Mar 2001 11:42:38 -0800 | From | David Brownell <> | Subject | Re: [linux-usb-devel] Re: SLAB vs. pci_alloc_xxx in usb-uhci patch [RFC: API] |
| |
> > > Do lots of drivers need the reverse mapping? It wasn't on my todo list > > > yet. > > > > I am against any API which provides this. It can be extremely > > expensive to do this on some architectures,
The implementation I posted needed no architecture-specific knowledge. If cost is the issue, fine -- this makes it finite, (not infinite), and some drivers can eliminate that cost.
> > and since the rest > > of the PCI dma API does not provide such an interface neither > > should the pool routines. > > The API I hacked together for uhci.c didn't have this.
But it didn't handle the OHCI done-list processing, and we've heard a lot more about pci_*_consistent being needed with OHCI than with UHCI; it's more common on non-Intel architectures.
Given that some hardware must return the dma addresses, why should it be a good thing to have an API that doesn't expose the notion of a reverse mapping? At this level -- not the lower level code touching hardware PTEs.
- Dave
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |