linux-kernel - Re: [PATCH 2/3] dt-bindings: PCI: ti,j721e-pci-*: Add checks for max-link-speed

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Message-ID: <9e71bb6c-5fac-4398-8048-88b0f7aabfe9@linaro.org>
Date: Wed, 17 Jan 2024 12:34:24 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Siddharth Vadapalli <s-vadapalli@...com>
Cc: bhelgaas@...gle.com, lpieralisi@...nel.org, kw@...ux.com,
 robh@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 vigneshr@...com, afd@...com, srk@...com
Subject: Re: [PATCH 2/3] dt-bindings: PCI: ti,j721e-pci-*: Add checks for
 max-link-speed

On 17/01/2024 12:22, Siddharth Vadapalli wrote:
> 
> 
> On 17/01/24 16:49, Krzysztof Kozlowski wrote:
>> On 17/01/2024 12:15, Siddharth Vadapalli wrote:
>>>
>>>
>>> On 17/01/24 16:30, Krzysztof Kozlowski wrote:
>>>> On 17/01/2024 11:58, Siddharth Vadapalli wrote:
>>>>> On 17/01/24 16:05, Krzysztof Kozlowski wrote:
>>>>>> On 17/01/2024 11:25, Siddharth Vadapalli wrote:
>>>>>>> Extend the existing compatible based checks for validating and enforcing
>>>>>>> the "max-link-speed" property.
>>>>>>
>>>>>> Based on what? Driver or hardware? Your entire change suggests you
>>>>>
>>>>> Hardware. The PCIe controller on AM64 SoC supports up to Gen2 link speed while
>>>>> the PCIe controllers on other SoCs support Gen3 link speed.
>>>>>
>>>>>> should just drop it from the binding, because this can be deduced from
>>>>>> compatible.
>>>>>
>>>>> Could you please clarify? Isn't the addition of the checks for "max-link-speed"
>>>>> identical to the checks which were added for "num-lanes", both of which are
>>>>> Hardware specific?
>>>>
>>>> Compatible defines these values, at least what it looks like from the patch.
>>>
>>> In this patch, I have added checks for the "max-link-speed" property in the same
>>> section that "num-lanes" is being evaluated. 
>>
>> I know what you did in patch. I read it.
>>
>>> The values for "max-link-speed" are
>>> based on the Hardware support and this patch is validating the "max-link-speed"
>>> property in the device-tree nodes for the devices against the Hardware supported
>>> values which this patch is adding in the corresponding section. Kindly let me
>>> know if I misunderstood what you meant to convey.
>>
>> Nothing of this is relevant.
>>
>> I used two entirely different wordings for this and you still don't get
>> it, so I don't know if I have third one.
>>
>> Maybe this:
>> Move it to driver match data.
> 
> Ok. I will drop the checks for "max-link-speed" and move them to the driver. But
> I wonder why the checks for "num-lanes" are needed in the first place when they
> could be in the driver as well.

Yes, that's why I commented in your next patch.

Best regards,
Krzysztof