Re: [PATCH] ARM: dts: qcom-apq8064: use correct pci address for address translation

[Lorenzo Pieralisi]

On Wed, May 09, 2018 at 02:01:34PM +0200, Niklas Cassel wrote:
> For PCI, the second and third cell in ranges specifies the upper and
> lower target address for address translation. This target address will
> be used to program the internal address translation unit (iATU).
> 
> The current device tree configuration will program the iATU to translate
> CPU accesses to 0x08000000 to PCI address 0x0 (with TLP type MEM).
> The device tree configuration also specifies that CPU acesses to
> 0x0fe00000 will be translated to PCI address 0x0 (with TLP type I/O).
> 
> We cannot have both I/O space and memory space at PCI address 0x0.
> 
> The PCI code already uses the CPU address when assigning addresses to
> memory BARs, so for memory space the PCI address should be the same as
> the CPU address. This also matches how all other device trees using
> snps,dw-pcie are configured.
> 
> The existing configuration appears to work, even if it is incorrect.
> For some reason the iATU doesn't obey the existing configuration,
> and doesn't translate CPU accesses from 0x08000000 to PCI address 0x0.
> 
> The reason why the existing configuration works at all is probably
> because the default behavior, when there is no match, is to use the
> untranslated address. This happens to work for memory space, since
> it's a 1:1 mapping. However, instead of relying on this behavior,
> let's configure the iATU correctly.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxxxxx>
> ---
>  arch/arm/boot/dts/qcom-apq8064.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Hi Niklas,

what's this patch status ? Please let me know if I have to keep
it in the PCI tree queue, I think, if ACKed, it should probably
go via the arm-soc tree.

Thanks,
Lorenzo

> diff --git a/arch/arm/boot/dts/qcom-apq8064.dtsi b/arch/arm/boot/dts/qcom-apq8064.dtsi
> index 5341a39c0392..148cf7e565f6 100644
> --- a/arch/arm/boot/dts/qcom-apq8064.dtsi
> +++ b/arch/arm/boot/dts/qcom-apq8064.dtsi
> @@ -1417,7 +1417,7 @@
>  			#address-cells = <3>;
>  			#size-cells = <2>;
>  			ranges = <0x81000000 0 0 0x0fe00000 0 0x00100000   /* I/O */
> -				  0x82000000 0 0 0x08000000 0 0x07e00000>; /* memory */
> +				  0x82000000 0 0x08000000 0x08000000 0 0x07e00000>; /* memory */
>  			interrupts = <GIC_SPI 238 IRQ_TYPE_NONE>;
>  			interrupt-names = "msi";
>  			#interrupt-cells = <1>;
> -- 
> 2.17.0
>