linux-kernel - Re: [PATCH v7 1/7] media: dt-bindings: venus: Add qcm2290 dt schema

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Message-ID: <1402a52f-639c-4872-a153-b549603c13a7@linaro.org>
Date: Fri, 18 Jul 2025 11:21:07 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Jorge Ramirez <jorge.ramirez@....qualcomm.com>
Cc: quic_vgarodia@...cinc.com, quic_dikshita@...cinc.com, krzk+dt@...nel.org,
 konradybcio@...nel.org, mchehab@...nel.org, andersson@...nel.org,
 conor+dt@...nel.org, amit.kucheria@....qualcomm.com,
 linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/7] media: dt-bindings: venus: Add qcm2290 dt schema

On 18/07/2025 11:04, Krzysztof Kozlowski wrote:
> On 18/07/2025 12:02, Konrad Dybcio wrote:
>> On 7/18/25 8:27 AM, Krzysztof Kozlowski wrote:
>>> On 17/07/2025 19:00, Jorge Ramirez wrote:
>>>> On 17/07/25 13:16:31, Jorge Ramirez wrote:

>>>> Not sure if I’ve shared this before, but following an internal
>>>> discussion, I think it’s worth highlighting a functional dependency in
>>>> the current kernel:
>>>>
>>>>   - the driver only works if the first two IOMMUs in the list — the
>>>> non-secure ones — are placed at the beginning. Reordering them breaks
>>>> functionality, which introduces unexpected fragility.
>>>>
>>>> Regardless, this seems like a valid concern to me — a driver shouldn't
>>>> rely on the order of phandles — and I just wanted to make sure you're
>>>> aware of it before I post a v8 (likely sometime next week or the
>>>> following, as I’ll be taking a short break soon).
>>>
>>>
>>> Hm? Order of lists is strictly defined. That's actually an overlook that
>>> we never do it for iommus, but the core rule stays.
>>
>> (FWIW "items:" is an ordered list, "enum:" is unordered)
> 
> enum is not a list, but enumeration, meaning one item of multiple values.
> 
> Best regards,
> Krzysztof

As Krzysztof says the ordering is strict.

I think the right-thing-to-do is to document in the commit log the 
dependency.

The final three entries are secure entries and the ordering is important.

---
bod