On Tue, 16 Oct 2007 18:44:17 -0700 [EMAIL PROTECTED] wrote: > @@ -547,3 +547,41 @@ size is the size (and should be a page-sized multiple). > The return value will be either a pointer to the processor virtual > address of the memory, or an error (via PTR_ERR()) if any part of the > region is occupied. > + > +int > +dma_flags_set_attr(u32 attr, enum dma_data_direction dir) > + > +Amend dir with a platform-specific "dma attribute". > + > +The only attribute currently defined is DMA_BARRIER_ATTR, which causes > +in-flight DMA to be flushed when the associated memory region is written > +to (see example below). Setting DMA_BARRIER_ATTR provides a mechanism > +to enforce ordering of DMA on platforms that permit DMA to be reordered > +between device and host memory (within a NUMA interconnect). On other > +platforms this is a nop. > + > +DMA_BARRIER_ATTR would be set when the memory region is mapped for DMA, > +e.g.: > + > + int count; > + int flags = dma_flags_set_attr(DMA_BARRIER_ATTR, DMA_BIDIRECTIONAL); > + .... > + count = dma_map_sg(dev, sglist, nents, flags); > +
Isn't this rather a kludge? What would be the cost of doing this cleanly and either redefining dma_data_direction to be a field-of-bits or just leave dma_data_direction alone (it is quite unrelated to this work, isn't it?) and adding new fields/arguments to manage this new functionality? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
