[PATCH v3 2/3] arm64: dts: Add APM X-Gene DMA device and DMA clock DTS nodes

Thanks,
with regards,
Ram


On Mon, Jan 19, 2015 at 8:11 PM, Rameshwar Sahu [off-list ref] wrote:

Hi Arnd,






Thanks,
with regards,
Ram

On Mon, Jan 19, 2015 at 7:10 PM, Arnd Bergmann [off-list ref] wrote:

quoted

On Monday 19 January 2015 18:11:08 Rameshwar Prasad Sahu wrote:

quoted

diff --git a/arch/arm64/boot/dts/apm/apm-storm.dtsi

b/arch/arm64/boot/dts/apm/apm-storm.dtsi
index f1ad9c2..e20da23 100644

--- a/arch/arm64/boot/dts/apm/apm-storm.dtsi
+++ b/arch/arm64/boot/dts/apm/apm-storm.dtsi

@@ -103,6 +103,9 @@
                #size-cells = <2>;
                ranges;

+               /* DDR range is 42-bit addressing */
+               dma-ranges = <0x40 0x0 0x40 0x0 0x1ff 0xffffffff>;
+

The comment above is misleading, and the value is wrong. I assume you

copied these from the AMD patch that introduced the respective property.

I referred this patch from AMD only.

quoted

The value should be

        dma-ranges = <0x40 0x0 0x40 0x0 0x200 0>;

then it should be :

dma-ranges = <0x40 0x0 0x40 0x0 0x400 0>;

quoted

to say that any DMA to physical addresses from 0 to 0x3f.ffffffff
is disallowed and dma to physical addresses from 0x40.00000000
to 0x23f.ffffffff is allowed and gets translated using an
identity mapping.

I also see that on Mustang, all memory is outside of this range,

Do you mean all other device controller node in DT here??
Basically these are all device controller memory, as what I understood is
dma-ranges tells about DDR ranges like start address of DDR
and length.

quoted

which is a bit suspicious, while your PCI memory space is
included.

quoted

It would be best to match the numbers up with your data sheet.

        Arnd
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