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. > >>> >>> >>> 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
