Re: [PATCH 07/14] riscv: dts: canaan: fix the k210's memory node

[<Conor.Dooley@microchip.com>]

On 27/06/2022 07:55, Krzysztof Kozlowski wrote:
> On 21/06/2022 11:49, Conor.Dooley@microchip.com wrote:
>> On 20/06/2022 01:25, Damien Le Moal wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> On 6/20/22 08:54, Conor.Dooley@microchip.com wrote:
>>>> On 20/06/2022 00:38, Damien Le Moal wrote:
>>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>>
>>>>> On 6/18/22 21:30, Conor Dooley wrote:
>>>>>> From: Conor Dooley <conor.dooley@microchip.com>
>>>>>>
>>>>>> The k210 memory node has a compatible string that does not match with
>>>>>> any driver or dt-binding & has several non standard properties.
>>>>>> Replace the reg names with a comment and delete the rest.
>>>>>>
>>>>>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>>>>>> ---
>>>>>> ---
>>>>>>    arch/riscv/boot/dts/canaan/k210.dtsi | 6 ------
>>>>>>    1 file changed, 6 deletions(-)
>>>>>>
>>>>>> diff --git a/arch/riscv/boot/dts/canaan/k210.dtsi b/arch/riscv/boot/dts/canaan/k210.dtsi
>>>>>> index 44d338514761..287ea6eebe47 100644
>>>>>> --- a/arch/riscv/boot/dts/canaan/k210.dtsi
>>>>>> +++ b/arch/riscv/boot/dts/canaan/k210.dtsi
>>>>>> @@ -69,15 +69,9 @@ cpu1_intc: interrupt-controller {
>>>>>>
>>>>>>         sram: memory@80000000 {
>>>>>>                 device_type = "memory";
>>>>>> -             compatible = "canaan,k210-sram";
>>>>>>                 reg = <0x80000000 0x400000>,
>>>>>>                       <0x80400000 0x200000>,
>>>>>>                       <0x80600000 0x200000>;
>>>>>> -             reg-names = "sram0", "sram1", "aisram";
>>>>>> -             clocks = <&sysclk K210_CLK_SRAM0>,
>>>>>> -                      <&sysclk K210_CLK_SRAM1>,
>>>>>> -                      <&sysclk K210_CLK_AI>;
>>>>>> -             clock-names = "sram0", "sram1", "aisram";
>>>>>>         };
>>>>>
>>>>> These are used by u-boot to setup the memory clocks and initialize the
>>>>> aisram. Sure the kernel actually does not use this, but to be in sync with
>>>>> u-boot DT, I would prefer keeping this as is. Right now, u-boot *and* the
>>>>> kernel work fine with both u-boot internal DT and the kernel DT.
>>>>
>>>> Right, but unfortunately that desire alone doesn't do anything about
>>>> the dtbs_check complaints.
>>>>
>>>> I guess the alternative approach of actually documenting the compatible
>>>> would be more palatable?
>>>
>>> Yes, I think so. That would allow keeping the fields without the DTB build
>>> warnings.
>>
>> Hmm looks like that approach contradicts the dt-schema;
>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/memory.yaml
>>
>> @Rob,Krzysztof what is one meant to do here?
> 
> Why do you think it contradict bindings? Bindings for memory allow

Because when I tried to write the binding, the memory node complained
about the clock properties etc and referenced the dt-schema (which
for memory@foo nodes has additionalProperties: false.

> additional properties, so you just need to create binding for this one.
> And make it a correct binding, IOW, be sure that these clocks are real etc.
> 
> Although usually we had separate bindings (and device drivers) for
> memory controllers, instead of including them in the "memory" node.

I guess changing to that format would probably require some changes on
the U-Boot side of things. Taking "calxeda,hb-ddr-ctrl" as an example,
looks like the clocks etc go in a controller node, which seems like a
"better" way of doing it - but would break existing dts in U-Boot
without changes to handle both methods there.

Thanks,
Conor.