On Tue, Aug 23, 2016 at 11:05 AM, Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote: > On 08/22/16 13:49, Ran Shalit wrote: >>>> I try to use dmaengine (using dart board), with dmatest.ko, >>> >>> With dmatest you can only test MEM_TO_MEM type of transfers, like memcpy, XOR, >>> etc. >>> >> >> I use omap4 connected to fpga. fpga implements fifo which cpu need to >> read/write from/to (iowrite16). >> I think it should be "memory to memory". >> From my understanding device to/from memory only required when device >> read/write from RAM while in this case we use fpga memory (which is >> mapped to cpu) >> Is that correct ? Can we use memory to memory ? > > If the fpga memory is mapped, then memcpy should be fine, if you have only one > address to read/write then memcpy will not work. You will need slave DMA. For > that to work you will need DMA request from the fpga. > >>>> but seems that nothing happens because /sys/class/dma is empty. >>> >>> How can your board even boot up w/o dma? >>> >> >> On doing "ls /sys/class/dma" I get no list of channels. >> I am not sure what it means. >> >> >>>> Is there a way to register the dma channels (using dart board file >>>> probably) so that they appear ? >>> >>> OMAP4 _needs_ dmaengine to be available in order to boot, do you have DMA_OMAP >>> enabled in your kernel? What is the kernel versiuon you are using? >>> >> >> The config has no DMA_OMAP (but has DMAENGINE enabled) >> The kernel version is 3.4.0 >> I wander how it boot without dma. Maybe dma is missing from /sys/config/dma ? >> >> I am also not sure where is the dma driver for omap (sdma) in this kernel. >> Should 3.4.0 omap dma driver support memory-to-memory , and 16bits >> transactions (this is required for the fpga) ? > > The sDMA dmaengine driver was introduced with 3.6, the memcpy support is > coming in at 4.2. > In 3.4 you only have the legacy omap-dma support. This explains why the > /sys/class/dma/ is empty for you. > Peter, Thank you very much. It seems that I can't upgrade the kernel at this point of development. So, I will have to do it with legacy API (since I can't updared) using omap-dma.c , memcpy transfer , 16-bits. I think it is possible, Right ? I see there is also example (mcbsp.c) for using legacy in: ftp://ftp.oregonstate.edu/.2/nslu2/sources/git/git.openmoko.org.git.kernel.git/arch/arm/plat-omap/mcbsp.c As I understand, the transfer word length is set with omap_set_dma_transfer_params(), used with OMAP_DMA_DATA_TYPE_S16 for 16-bits with . Another last thing: Do we need to confure dma channels in board file (I can't see any reference to dma) ? Thank you, Ran >> >>>> >>>> >>>> Regards, >>>> Ran >>>> >>>> >>>>>> >>>>>>> >>>>>>>> 2.Is there any example which shows how to use DMA (which shall call >>>>>>>> the edma, and shall result in triggering a dma trsnaction in OMAP) ? >>>>>>> >>>>>>> git grep dmaengine_prep_dma_sg >>>>>>> or >>>>>>> git grep dmaengine_terminate_all >>>>>>> >>>>>>> will show you the drivers using dmaengine. >>>>>>> >>>>>>> -- >>>>>>> Péter >>>>>> >>>>> >>>>> >>>>> -- >>>>> Péter >>> >>> >>> -- >>> Péter > > > -- > Péter -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
