Hi, In dma_request_chan_by_mask() , the probe defer logic returns -EPROBE_DEFER if there are no DMA devices registered yet. But in case of multiple DMA controllers in an SoC and when only one(or a subset) of the controllers have finished probe dma_request_chan_by_mask() can return -ENODEV incorrectly since the first DMA device probed might not support the particular mask requested. What is the recommended solution to avoid situation like these? Consider the following scenario for example: SoC has two DMA controllers, one instance of system DMA, one dedicated for Camera subsytem which does not support DMA_MEMCPY and has lesser number of channels. * Camera subsystem DMA is probed first. * Another peripheral requests dma_request_chan_by_mask(DMA_MEMCPY) * dmaengine returns -ENODEV for above as the controller with DMA_MEMCPY support is not ready yet. * System DMA is probed later but peripheral driver failed to start with DMA. -- Thanks and Regards, Vaishnav
