On Friday 26 September 2014 08:23:40 Peter Chen wrote: > In current chipidea structure, the parent (glue layer) driver will not be > used for dma, udc/host driver uses dma mask from child (core layer), at core > layer we will do: > > > pdev->dev.dma_mask = dev->dma_mask; /* this device is parent */ > dma_set_coherent_mask(&pdev->dev, dev->coherent_dma_mask); > > Would you suggestion us a suitable way? Or it is ok we use just Antoine's way that > call dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)) at parent > driver no matter dt or non-dt? Thanks. dma_coerce_mask_and_coherent is not ok, it will force a dma mask that is unrelated to the actual requirements of the hardware. I think the best way would be to never use the child device pointer for DMA operations, just use a pointer to the parent device and make the child dev->dma_mask pointer NULL to ensure all DMA operations fail. 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
