On 08/02/2017 04:09 PM, Peter Ujfalusi wrote: > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki > > On 2017-08-02 16:11, Pierre Yves MORDRET wrote: >> Our SoC works with or without DMAMUX. Both binding is allowed. Using only DMA a >> ChannelId and request line is part of the binding. > > In our case the am335x's eDMA can work with or without the router, we > only use the router node if we need none default event for a given DMA > request line. > >> Using DMAMUx now the request >> line is coming from dma_spec forwards to dma-master as well explained by Peter. >> However ChannelID is now given by dma_get_any_slave_channel instead of bindings. >> DMAMUX driver has to be aware of this ID to route request line to out DMA >> channel. This channel id information is carried on until DMAMUX through >> dmaengine_slave_config with a custom API. >> Hope it clarifies the need. > > I see, this is not much different then what we face with our dra7 > devices. In theory we could use direct DMA binding to the DMA controller > itself, but some requests would not be reachable, so we always use the > router's node for DMA on dra7 family. > > Basically the router would manage the ChannelID and create > 'st,stm32-dma' compatible dma_spec (the four parameters). > Afaik you could have 3 parameters for the router and create a four > parameter dma_spec, where the ChannelID is dynamically allocated. Correct router needs 3 parameters and among those 2 are forwarded though out dma_spec. But when you say "ChannelID is dynamically allocated" you mean dma_get_any_slave_channel ? If yes I can use the already existing bindings to carry the channelID to DMA. No changes need to peripheral... > But you need to convert all peripherals to use the router's node for the > DMA. > > - Péter > Py -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
