Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev

Arnd Bergmann
2016-09-02T13:11:12Z

On Friday, September 2, 2016 12:55:33 PM CEST Robin Murphy wrote:
>
> Huh? There's only no DMA description in DT if the device can be assumed
> to be happy with the defaults. Anything else should be using
> "dma-ranges", "dma-coherent", etc. to describe non-default integration
> aspects. For devices with an inherent fixed addressing capability !=32
> bits, then it's down to the driver to call dma_set_mask() appropriately
> to override the default 32-bit mask (which is not unique to OF-probed
> devices either).

The iommu configuration would be the main other one worth mentioning.

Note that there is a known bug with dma_set_mask(), which always succeeds
at the moment, even if the dma-ranges limit the possible addresses
in a way that should fail.

Arnd