On 12/27/2015 04:31 PM, Ran Shalit wrote: > Hello, > > The following question is not totally in the scope of v4l2, but more > about your advise concering dma alternatives for non-expreciened v4l2 > device writer. > We intend to use the fpga for concurrent 3xHD and 3xSD. > > We have some dillema regadring the fpga to choose from: > ALTERA fpga which use contiguous dma memory, or Xilinx fpga which is > using scatter-gather architecture. > > With xilinx, it seems that the sg architecture can also be used as > contiguous according to the following: > "... While these descriptors are not required to be contiguous, they > should be contained within an 8 megabyte region which corresponds to > the width of the AXI_PCIe_SG port" I think they are talking about the memory containing the descriptors themselves. I.e. the scatter-gather list should be in contiguous memory that is no more than 8 megabytes long. This is normally not a problem. I don't think they are talking about the DMA itself, that should be pretty much unlimited. Regards, Hans > it seems according to the above description that sg-list can be used > as single contiguous descriptor (with dma-cotig), though the 8MBytes > seems like a problematic constrain. This constrain make it difficult > to be used with dma-contig solution in v4l2. > > Our current direction is try to imeplement it as simple as possible. > Therefore we prefer the dma contiguous solution (I think that together > with CMA and a strong cpu like 64-bit i7 it can handle contigious > memory for 3xHD and 3xSD allocation). > > Any feedback is appreciated, > Ran > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
