Re: [PATCH 01/13] dt-bindings: memory: snps: Extend schema with IRQs/resets/clocks props

Krzysztof Kozlowski
2022-08-30T15:02:06Z

On 26/08/2022 11:47, Serge Semin wrote:

>>
>>> +
>>> + interrupt-names:
>>> + minItems: 1
>>> + maxItems: 5
>>> + oneOf:
>>> + - description: Common ECC CE/UE/Scrubber/DFI Errors IRQ
>>> + items:
>>> + - const: ecc
>>> + - description: Individual ECC CE/UE/Scrubber/DFI Errors IRQs
>>> + items:
>>> + enum: [ ecc_ce, ecc_ue, ecc_ap, ecc_sbr, dfi_e ]
>>>
>>> reg:
>>> maxItems: 1
>>>
>>> + clocks:
>>> + description:
>>> + A standard set of the clock sources contains CSRs bus clock, AXI-ports
>>> + reference clock, DDRC core clock, Scrubber standalone clock
>>> + (synchronous to the DDRC clock).
>>> + minItems: 1
>>> + maxItems: 4
>>
>
>> I expect list to be strictly defined, not flexible.
>
> Some of the clock sources might be absent or tied up to another one
> (for instance pclk, aclk and sbr can be clocked from a single core
> clock source). It depends on the IP-core synthesize parameters.

Yet still your device has clock lines - clock inputs, right? Therefore
still 4 clocks will be going there or you want to say that the pin is
not connected (or pulled down)?

>
>>
>>> +
>>> + clock-names:
>>> + minItems: 1
>>> + maxItems: 4
>>> + items:
>>> + enum: [ pclk, aclk, core, sbr ]
>>> +
>>> + resets:
>>> + description:
>>> + Each clock domain can have separate reset signal.
>>> + minItems: 1
>>> + maxItems: 4
>>> +
>>> + reset-names:
>>> + minItems: 1
>>> + maxItems: 4
>>> + items:
>>> + enum: [ prst, arst, core, sbr ]
>>
>
>> The same.
>
> The same as for the clock.
>
>>
>>> +
>>> required:
>>> - compatible
>>> - reg
>>> @@ -48,4 +92,15 @@ examples:
>>> interrupt-parent = <&gic>;
>>> interrupts = <0 112 4>;
>>> };
>>> + - |
>>> + memory-controller@fd070000 {
>>> + compatible = "snps,ddrc-3.80a";
>>> + reg = <0x3d400000 0x400000>;
>>> +
>>> + interrupts = <0 147 4>, <0 148 4>, <0 149 4>, <0 150 4>;
>>
>
>> Use proper defines.
>
> What do you mean? Which defines do you think would be proper? If you
> meant the IRQ DT-bindings macros, then what difference does it make
> for a generic device in the DT-binding example?

The macros/defines representing these numbers.

> Note since the device
> is defined as generic it can be placed on different platforms with
> different interrupt controller requirements. So what do you mean by
> "proper" in this case?

Proper means text instead of hard-coded number. This piece of code has
meaning in a specific context, because you used interrupts matching some
specific interrupt controllers. In that controller context, the "4" has
a meaning. Just like "0". You cannot say that this piece of code is
interrupt-controller-independent, because it is not. 4 has meaning.

If you want it to be independent, drop all the flags... If you use flags
from a specific implementation, then use proper defines matching them,
not hard-coded numbers.

Best regards,
Krzysztof