Re: [PATCH v3 06/11] dt-bindings: PCI: Update the RK3399 example to a valid one

[Krzysztof Kozlowski]

On 04/04/2023 10:58, Rick Wertenbroek wrote:
> On Tue, Apr 4, 2023 at 10:45 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@xxxxxxxxxx> wrote:
>>
>> On 04/04/2023 10:24, Rick Wertenbroek wrote:
>>> Update the example in the documentation a valid example.
>>> The default max-outbound-regions is 32 but the example showed 16.
>>
>> This is not reason to be invalid. It is perfectly fine to change default
>> values to desired ones. What is not actually obvious is to change some
>> value to a default one, instead of removing it...
> 
> Hello, the example value <0x0 0x80000000 0x0 0x20000>; is plain wrong
> and will crash the kernel. This is a value that point to an address that falls
> in the DDR RAM region but depending on the amount of RAM on the
> board this address may not even exist (e.g., board with 2GB or less).

We talk about max-outbound-regions.

> 
> Also this address requires pointing to where the PCIe controller has the
> windows from AXI Physical space to PCIe space. This address is
> allocated when the SoC address map is created so it can only be that
> one unless rockchip refabs the SoC with another address map.
> 
> The example never worked with the values given as reported by e.g.,
> https://stackoverflow.com/questions/73586703/device-tree-issues-with-rockpro64-pcie-endpoint
> and here they set it to 0 (base of the DDR, which is a "valid" address
> as to it exists even on boards with less than 2GB) but it is still wrong
> to do so.

Again, my comment was under max-outbound-regions, not under some other
pieces. Does this all apply?

Best regards,
Krzysztof