On Wed, Aug 03, 2016 at 10:05:38AM +0000, Radhey Shyam Pandey wrote: > Hi Vinod, > > > > > > I am planning to write DMA driver for new Xilinx VDMA IP (HLS Based) > > > and integrate it with Xilinx V4L2 capture pipeline. > > > > It should be update on existing VDMA driver then? > Yes initially we thought similar but in later design discussions we came up > with idea to add a new dma driver since there was no code reusability/common > code between two DMA IP's variant. I would not be so sure about that! > > > For single DMA read/write transaction hardware requires two physically > > > separate buffers for Y and CbCr components, which must be placed in > > > two different memory banks. i.e DMA reads YUV AXI-Stream for > > > source(DEV) and put it MEM into planar format. > > > > > > > > > V4L2_PIX_FMT_NV16 (Description) > > > > > > So I need some attribute in struct dma_channel to indicate that it > > > supports packed/planar format? > > > > > > Also while programming DMA we need to provide the base address of Y > > > plane and UV plane to hardware for one DMA transaction. Current > > > dmaengine_prep_* implementations doesn't provide an interface to > > > program multiplanar channel address. > > > > Sounds like interleaved API could be used here? > interleaved DMA transfer template has src_start and dst_start to provide bus > address of source/destination of first chunk. Yes > For multiplanar support requirement is to program multiple source/destination > buffer addr for single DMA transaction. why cant a trxn from user be split to multiple dmanegine txn's? > One idea is to extend transfer template to provide array of src/destination > address. Any alternative solution to support this usecase? > > Example: > Test Patter Generator / VIVID - > (YUV 4:2:2) -> > Y will be written to one plane and UV to other plane i.e start0 and start1 > address. > > V4L2_PIX_FMT_NV16M 4 × 4 pixel image > > Byte Order. Each cell is one byte. > > start0 + 0: Y'00 Y'01 Y'02 Y'03 > start0 + 4: Y'10 Y'11 Y'12 Y'13 > start0 + 8: Y'20 Y'21 Y'22 Y'23 > start0 + 12: Y'30 Y'31 Y'32 Y'33 > > start1 + 0: Cb00 Cr00 Cb02 Cr02 > start1 + 4: Cb10 Cr10 Cb12 Cr12 > start1 + 8: Cb20 Cr20 Cb22 Cr22 > start1 + 12: Cb30 Cr30 Cb32 Cr32 Sounds like you should actually do multiple txn's with dmanegine.. -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
