On 9/14/19 6:33 PM, Geert Uytterhoeven wrote: > Hi Marek, Hi, > On Sat, Sep 14, 2019 at 6:06 PM Marek Vasut wrote: >> On 9/9/19 1:18 PM, Geert Uytterhoeven wrote: >>> On Sat, Sep 7, 2019 at 6:16 PM Marek Vasut wrote: >>>> Add dma-ranges property into /soc node to describe the DMA capabilities >>>> of the bus. This is currently needed to translate PCI DMA ranges, which >>>> are limited to 32bit addresses. >>> >>>> --- a/arch/arm64/boot/dts/renesas/r8a7795.dtsi >>>> +++ b/arch/arm64/boot/dts/renesas/r8a7795.dtsi >>>> @@ -330,6 +330,7 @@ >>>> #address-cells = <2>; >>>> #size-cells = <2>; >>>> ranges; >>>> + dma-ranges = <0 0x40000000 0 0x40000000 0 0xc0000000>; >>> >>> Shouldn't the length be 0x80000000 (for all SoCs)? >> >> Or should that match the amount of DRAM below 32bit boundary ? > > Which is 0x80000000, according to the memory area section for the > various R-Car Gen3 SoCs. What if you have a system with 1 GiB of DRAM ? >>> Or should we allow DMA to internal System RAM, too? >> >> I think we should include SRAM, yes. > > So that needs a separate range. Let's see how the discussion pans out about the placement of the dma-ranges in the first place. -- Best regards, Marek Vasut
