Messages in this thread | | | Date | Sun, 2 Oct 2011 00:15:25 +0530 | Subject | Re: [PATCHv4] DMAEngine: Define interleaved transfer request api | From | Jassi Brar <> |
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On 1 October 2011 23:41, Vinod Koul <vinod.koul@intel.com> wrote: > On Sat, 2011-10-01 at 11:05 +0800, Barry Song wrote: >> 2011/10/1 Jassi Brar <jaswinder.singh@linaro.org>: >> > On 30 September 2011 12:13, Barry Song <21cnbao@gmail.com> wrote: >> >> >> >> i support we can update dma_data_direction to: MEM_TO_MEM, >> >> MEM_TO_DEV, DEV_TO_MEM, DEV_TO_DEV. >> >> >> > So basically you are suggesting to replace 'enum dma_data_direction' >> > with 'enum xfer_direction' >> > I am not sure about that. I think they represent different things and >> > hence should be separate. >> > dma_data_direction tells the mapping of a buffer while the other >> > tells if the src and dst are memory or a device's FIFO. >> > >> you are kind of right now. now people use dma_data_direction to do >> mapping for dma buffer. even with all 4 direction, people still use >> the old two direction to do mapping. For example, it can't use >> MEM_TO_MEM to map, it still need to know whether the memory is source >> or dest. >> >> i just don't like to the two old macro names. it seems i get a ticket >> flying from New York to Beijing, but actually, we fly to Mexico... >> so by the moment, dma_data_direction seems just to mean how to do map, >> but xfer_direction is the real transfer direction. >> >> How could we have two macro names: SRC_MEM, DEST_MEM for mapping. or just add: >> dma_map_single_src >> dma_map_single_dst > Direction is valid even if you are doing memory to memory transfer. IMO > what we need to specify what type of transfer (memory or peripheral), > perhaps a flag and use that along with dma_data_direction. I think dma_data_direction should be moved into dmac drivers that decide the value from _more_ complete transfer info i.e, xfer_direction IOW let clients pass more precise info to the dmac drivers via xfer_direction.
> @Jassi, this is what kind of tweak I have in mind. And i do not agree > current approach is bad and is it cleanly tell us type of transfer > (memcpy or prep_sg) and direction with dma_data _direction. Not sure how is that "updating" the dma_data_direction ? Please clarify what you exactly propose. -- 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/
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