On Thursday 11 December 2014 08:37:27 Wolfram Sang wrote: > > I think this is a limitation of driver may not be for HW. The right model > > for dma_chan is to be viewed as SW channels and not the ones of HW (yes > > that is how most of the drivers use that, but we can improve upon) > > > > If we rework the driver to view dma_chan as SW channels, then you can > > accept multiple channel requests and accept based on if we are able link > > the channel to that peripheral or not. > > In my understanding, the DMA driver does exactly that. Actually it doesn't at the moment, I should implement that. > However, it is not even loaded at the time the I2C driver wants a channel, > so the dmaengine core defers the probe. That is the problem for optional DMA > channels: we can't know when deferring probe won't help anymore and don't > know when it is time to fall back to PIO. This is true regardless of the whether the driver exposes HW or SW channels. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
