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*. Thanks Kishon -- 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