Messages in this thread | | | Date | Sat, 28 Dec 2002 09:41:49 -0800 | From | David Brownell <> | Subject | Re: [RFT][PATCH] generic device DMA implementation |
| |
James Bottomley wrote: > OK, the attached is a sketch of an implementation of bus_type operations.
Quick reaction ....
Those signatures look more or less right, at a quick glance, except that allocating N bytes should pass a __GFP_WAIT flag. (And of course, allocating a mapping needs a failure return.)
That bus_dma_ops is more of a "vtable" approach, and I confess I'd been thinking of hanging some object that had internal state as well as method pointers. (Call it a "whatsit" for the moment.)
That'd make it possible for layered busses like USB and SCSI to just reference the "whatsit" from the parent bus in their layered "struct device" objects. [1]
In many cases that'd just end up being a ref to the "platform whatsit", eliminating a conditional test from the hot path from your sketch as well as an entire set of new "platform_*()" APIs.
- Dave
[1] That is, resembling what Benjamin Herrenschmidt suggested:
http://marc.theaimsgroup.com/?l=linux-kernel&m=102389432006266&w=2
- 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/
| |