Hello, On Monday, August 08, 2011 5:22 PM Ramirez Luna, Omar wrote: > On Sun, Jul 31, 2011 at 7:57 PM, KyongHo Cho <pullip.cho@xxxxxxxxxxx> wrote: > > On Fri, Jul 29, 2011 at 11:24 PM, Marek Szyprowski > ... > >> Right now I have no idea how to handle this better. Perhaps with should be > >> possible > >> to specify somehow the target dma_address when doing memory allocation, but I'm > >> not > >> really convinced yet if this is really required. > >> > > What about using 'dma_handle' argument of alloc_coherent callback of > > dma_map_ops? > > Although it is an output argument, I think we can convey a hint or > > start address to map > > to the IO memory manager that resides behind dma API. > > I also thought on this one, even dma_map_single receives a void *ptr > which could be casted into a struct with both physical and virtual > addresses to be mapped, but IMHO, this starts to add twists into the > dma map parameters which might create confusion. Nope, this is completely wrong approach. DMA-mapping is kernel wide, architecture independent API and you should not define any exceptions from it. > > DMA API is so abstract that it cannot cover all requirements by > > various device drivers;; > > Agree. >From my perspective DMA API is quite well designed as cross-architecture API. The only problem is the lack of documentation how to use it correctly in the embedded world. Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>