On Wednesday 14 May 2014 11:14:45 Kishon Vijay Abraham I wrote: > hi Arnd, > > On Tuesday 13 May 2014 07:04 PM, Arnd Bergmann wrote: > > On Tuesday 13 May 2014 15:27:46 Arnd Bergmann wrote: > >> On Tuesday 13 May 2014 18:56:23 Kishon Vijay Abraham I wrote: > >>>> If you have a case where the outbound translation is a 256MB (i.e. 28bit) > >>>> section of the CPU address space, that could be represented as > >>>> > >>>> ranges = <0x82000000 0 0 0xb0000000 0 0x10000000>; > >>>> > >>>> or > >>>> > >>>> ranges = <0x82000000 0 0xb0000000 0xb0000000 0 0x10000000>; > >>>> > >>>> depending on whether you want the BARs to be programmed using a low > >>>> address 0x0-0x0fffffff or an address matching the window > >>>> 0xb0000000-0xbfffffff. > >>> > >>> The problem is, for configuring the window starting at 0xb0000000, the ATU > >>> should be programmed 0x0000000 (the cpu address for it will be 0xb0000000 though). > >>> > >> > >> Then use the first of the two? > >> > > > > To clarify: using <0x82000000 0 0 0xb0000000 0 0x10000000> will give you > > a mem_offset of 0xb0000000, which should work just fine for this case. > > > > What I don't understand is why the ATU cares about whether the outbound > > address is 0x0000000 or 0xb0000000 if it just decodes the lower 28 bit > > anyway. Did you mean that we have to program the BARs using low addresses > > regardless of what is programmed in the ATU? That would make more sense, > > and it also matches what I suggested. > > No, It's not like it decodes only the lower 28bits. The BARs is programmed with > 32 bit value. > > My pcie dt node has > ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00002000 /* CONFIG */ > 0x81000000 0 0 0x20003000 0 0x00010000 /* IO */ > 0x82000000 0 0x20013000 0x20013000 0 0xffed000>; /* MEM */ > > Consider MEM address space.. > > Here both PCI address and CPU address is 0x20013000. So when there is a write > to cpu addr 0x20013000 [writel(virt_addr(0x20013000)], we want it to be > translated to PCI addr 0x20013000. So in 'ATU', we would expect *base* to be > programmed to *0x20013000* and target to be programmed to *0x20013000*. But > that's not the case for DRA7xx. For DRA7xx *base* should be programmed to > *0x0013000* and target should be programmed to *0x20013000*. Ok, got it, thanks for your patience. I think this would best be modeled as a separate bus node that contains the restriction, like this: / { #address-cells = <1>; // or <2> if you support > 4GB address space #size-cells = <1>; soc { #address-cells <1>; #size-cells = <1>; ranges; dma-ranges; ... // all normal devices axi@20000000 { #size-cells = <1>; #address-cells = <1>; dma-ranges; // can access all 4GB outbound ranges = <0 0x20000000 0x10000000>; // 28-bit bus pci@0 { reg = <0x0 0x1000>, // internal regs <0x1000 0x2000>; // config space dma-ranges; // 32-bit outbound ranges = <0x81000000 0 0 0x3000 0 0x00010000 /* IO */ 0x82000000 0 0x20013000 0x13000 0 0xffed000>; /* MEM */ }; }; }; }; 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