On Thursday 08 October 2015 18:01:23 M'boumba Cedric Madianga wrote: > Hi Arnd, > > 2015-10-08 17:43 GMT+02:00 Arnd Bergmann <arnd@xxxxxxxx>: > > On Thursday 08 October 2015 17:20:09 M'boumba Cedric Madianga wrote: > >> +Each dmas request consists of 5 cells: > >> +1. A phandle pointing to the STM32 DMA controller > >> +2. The channel id > >> +3. The request line number > >> +4. A 32bit mask specifying the DMA channel configuration > >> > > > > It's fairly unusual to encode the channel id here, rather than > > letting the driver pick one. Is that actually required here? > > Yes it is required as in STM32 platform the channel/request DMA > mapping is done by hardware lines. > So, if one client wants to use DMA, he has to choose the correct > channel/request values according to the DMA mapping of his STM32 > platform. Interesting. So you have seven channels ans seven request lines, with a random but fixed mapping between them? How do you know which channels are available for memory-to-memory transfers? Arnd -- 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
