linux-kernel - Re: [PATCH v3 0/5] Introduce "non-pixel" sub node within iris video node

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4cb4a92d-2f20-47c7-881e-aadcc6f83aa0@kernel.org>
Date: Tue, 7 Oct 2025 15:44:36 +0100
From: Bryan O'Donoghue <bod@...nel.org>
To: Bryan O'Donoghue <bod.linux@...w.ie>,
 Charan Teja Kalla <charan.kalla@....qualcomm.com>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Krzysztof Kozlowski <krzk@...nel.org>,
 Vikash Garodia <quic_vgarodia@...cinc.com>,
 Dikshita Agarwal <quic_dikshita@...cinc.com>,
 Abhinav Kumar <abhinav.kumar@...ux.dev>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, linux-media@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/5] Introduce "non-pixel" sub node within iris video
 node

On 07/10/2025 15:29, Bryan O'Donoghue wrote:
> On 07/10/2025 15:25, Bryan O'Donoghue wrote:
>> Rob suggested using an implicit index for function id
>>
>> https://lore.kernel.org/all/CAL_JsqK9waZK=i+ov0jV- 
>> PonWSfddwHvE94Q+pks4zAEtKc+yg@...l.gmail.com/
>>
>> Couldn't we list the entire set of iommus - then detach - subsequently
>> re-attaching in our platform code with FUNCTION_IDs we keep listed in
>> our drivers ?
>>
>> That way the DT is complete and correct, we have a compliant upstream DT
>> but we also find a way to make the FUNCTION_ID specific setup we need.
> 
> i.e. you can keep the FUNCTION_ID "metadata" in the driver and associate 
> specific iommu indexes with the FUNCTION_ID you want in there.
> 
> That way you could have multiple FUNCTION_ID smmu entries in the DT and 
> just associate the DT indexes locally in drivers/platform/qcom/ 
> iris_metadata_goes_here.c
> 
> ---
> bod

Actually why can't we specify FUNCTION_ID in the iommus = <entries>

Surely we could do

     #iommu-cells = <4>;
     iommus = <&apps_smmu 0x420 0x2 FUNCTION_ID>;

and encode the real data we need directly in the iommus list...

---
bod