On 08/23/16 13:12, Ran Shalit wrote: >> 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 ? Sure, if there is no dmaengine for sDMA, the legacy API is the only way to use sDMA. It is just a matter of how you configure the omap-dma, the API allows pretty much to use all features of sDMA. > 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 Hrm, this is more like 2.6.29-ish code... > 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 . McASP is using hw trigger, not sw trigger. It is not memcpy at all. Not sure if 2.6.29 had any memcpy users of sDMA. > Another last thing: > Do we need to confure dma channels in board file (I can't see any > reference to dma) ? This is only needed if the device have DMA request. In that case you want to have the hw request number as DMA resource on the device. But for memcpy you should not have hw request number as memcpy is sw triggered. > 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 -- 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
