On Fri, Apr 15, 2016 at 10:44 AM, Timur Tabi <ti...@codeaurora.org> wrote: > Rob Herring wrote: >>> >>> > >>> > dma-mask = <0 0xffffffff>; >>> > >>> >or >>> > >>> > dma-mask = <0xffffffff 0xffffffff>; >> >> No. See dma-ranges. > > > How exactly should I use dma-ranges? I can't find any other drivers that > queries that property and uses the result to call dma_set_mask. I thought > the dma-ranges property is intended to specify address translation. I don't > need to translate any address, I just need to know a single number.
You may only care about the size, but the binding has to handle the more complex case. Here's an example <0x0 0x2 0x0 0x1 0x0> dma address 0 (cell 0) maps to cpu (parent) address 0x2_00000000 (cell 1-2) and the range/size is 4G (cell 3-4). If you have the same base address, then use the same address. The core will calculate the mask based on the size. IIRC, we also handle ~0 as a special case to support 4G for #size-cell=1. Rob
