linux-kernel - Re: [PATCH v2 3/8] dt-bindings: media: mediatek,jpeg: Relax IOMMU max item count

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Message-ID: <dbe0927e-2d7b-4a32-a155-206566d543a8@gmail.com>
Date: Wed, 2 Oct 2024 15:12:38 +0200
From: Matthias Brugger <matthias.bgg@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Fei Shao <fshao@...omium.org>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Bin Liu <bin.liu@...iatek.com>, Conor Dooley <conor+dt@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Xia Jiang <xia.jiang@...iatek.com>, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2 3/8] dt-bindings: media: mediatek,jpeg: Relax IOMMU max
 item count



On 02/10/2024 08:16, Krzysztof Kozlowski wrote:
> On Tue, Oct 01, 2024 at 07:27:21PM +0800, Fei Shao wrote:
>> On MediaTek platforms with Multimedia MMU (M4U), a multimedia hardware
>> can be assigned with a local arbiter (LARB) which has a maximum of 32
>> ports for MediaTek's IOMMU infrastructure. That means there can be at
>> most 32 items in the iommus property in theory.
>>
>> Instead of relaxing the max item count every time a newly introduced
>> device tree hits the limit, bump the number to 32 as an one-time effort.
>>
>> On the other hand, all existing and foreseeable JPEG decoder nodes at
>> this point have at least 2 IOMMUs, so set minItems to 2 accordingly.
>>
>> Signed-off-by: Fei Shao <fshao@...omium.org>
>> ---
>> It's not in the upstream tree yet, but the upcoming MT8188 DT will have
>> 6 IOMMUs in its JPEG decoder. This patch is to pave the way for that.
>>
>> Changes in v2:
>> New patch.
>>
> 
> I do not see any user of this in this patchset.
> 

I'm not sure I understand you: the binding describes the hardware. If it can 
have up to 32 ports, then this should be reflected in the binding.

Regards,
Matthias