linux-kernel - Re: [PATCH v5 1/2] dt-bindings: memory: mediatek: Add SMI reset and clamp for MT8188

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Message-ID: <174172361378.44650.15345202042780383326.robh@kernel.org>
Date: Tue, 11 Mar 2025 15:07:02 -0500
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Friday Yang <friday.yang@...iatek.com>
Cc: linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
	Yong Wu <yong.wu@...iatek.com>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Project_Global_Chrome_Upstream_Group@...iatek.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] dt-bindings: memory: mediatek: Add SMI reset and
 clamp for MT8188


On Tue, 11 Mar 2025 20:23:21 +0800, Friday Yang wrote:
> From: "Friday Yang" <friday.yang@...iatek.com>
> 
> On the MediaTek platform, some SMI LARBs are directly connected to
> the SMI Common, while others are connected to the SMI Sub-Common,
> which in turn is connected to the SMI Common. The hardware block
> diagram can be described as follows.
> 
>              SMI-Common(Smart Multimedia Interface Common)
>                  |
>          +----------------+------------------+
>          |                |                  |
>          |                |                  |
>          |                |                  |
>          |                |                  |
>          |                |                  |
>        larb0       SMI-Sub-Common0     SMI-Sub-Common1
>                    |      |     |      |             |
>                   larb1  larb2 larb3  larb7       larb9
> 
> For previous discussion on the direction of the code modifications,
> please refer to:
> https://lore.kernel.org/all/CAFGrd9qZhObQXvm2_abqaX83xMLqxjQETB2=wXpobDWU1CnvkA@mail.gmail.com/
> https://lore.kernel.org/all/CAPDyKFpokXV2gJDgowbixTvOH_5VL3B5H8eyhP+KJ5Fasm2rFg@mail.gmail.com/
> 
> On the MediaTek MT8188 SoC platform, we encountered power-off failures
> and SMI bus hang issues during camera stress tests. The issue arises
> because bus glitches are sometimes produced when MTCMOS powers on or
> off. While this is fairly normal, the software must handle these
> glitches to avoid mistaking them for transaction signals. What's
> more, this issue emerged only after the initial upstreaming of this
> binding. Without these patches, the SMI becomes unstable during camera
> stress tests.
> 
> The software solutions can be summarized as follows:
> 
> 1. Use CLAMP to disable the SMI sub-common port after turning off the
>    LARB CG and before turning off the LARB MTCMOS.
> 2. Use CLAMP to disable/enable the SMI sub-common port.
> 3. Implement an AXI reset for SMI LARBs.
> 
> This patch primarily add two changes:
> 1. Add compatible for SMI sub-common on MT8188 SoC.
> 2. Add 'resets' and 'reset-names' properties for SMI LARBs to
>    support SMI reset operations.
> 
> Signed-off-by: Friday Yang <friday.yang@...iatek.com>
> ---
>  .../mediatek,smi-common.yaml                  |  2 ++
>  .../memory-controllers/mediatek,smi-larb.yaml | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 

Acked-by: Rob Herring (Arm) <robh@...nel.org>