linux-kernel - Re: [PATCH v4 1/2] dt-bindings: memory: mediatek: Add SMI reset and clamp for MT8188

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Message-ID: <0dcb2efd-6bbb-4701-960a-74930eb457e4@collabora.com>
Date: Mon, 24 Feb 2025 09:41:15 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Friday Yang <friday.yang@...iatek.com>, Yong Wu <yong.wu@...iatek.com>,
 Krzysztof Kozlowski <krzk@...nel.org>, Rob Herring <robh@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Matthias Brugger
 <matthias.bgg@...il.com>, Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v4 1/2] dt-bindings: memory: mediatek: Add SMI reset and
 clamp for MT8188

Il 21/02/25 08:48, Friday Yang ha scritto:
> 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@...l.gmail.com/
> https://lore.kernel.org/all/CAPDyKFpokXV2gJDgowbixTvOH_5VL3B5H8ey
> hP+KJ5Fasm2rFg@...l.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 | 20 +++++++++++++++++++
>   2 files changed, 22 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-common.yaml b/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-common.yaml
> index 2f36ac23604c..4392d349878c 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-common.yaml
> +++ b/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-common.yaml
> @@ -39,6 +39,7 @@ properties:
>             - mediatek,mt8186-smi-common
>             - mediatek,mt8188-smi-common-vdo
>             - mediatek,mt8188-smi-common-vpp
> +          - mediatek,mt8188-smi-sub-common
>             - mediatek,mt8192-smi-common
>             - mediatek,mt8195-smi-common-vdo
>             - mediatek,mt8195-smi-common-vpp
> @@ -107,6 +108,7 @@ allOf:
>           compatible:
>             contains:
>               enum:
> +              - mediatek,mt8188-smi-sub-common
>                 - mediatek,mt8195-smi-sub-common
>       then:
>         required:
> diff --git a/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml b/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml
> index 2381660b324c..2e86bb3455f9 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml
> +++ b/Documentation/devicetree/bindings/memory-controllers/mediatek,smi-larb.yaml
> @@ -69,6 +69,12 @@ properties:
>       description: the hardware id of this larb. It's only required when this
>         hardware id is not consecutive from its M4U point of view.
> 
> +  resets:
> +    maxItems: 1
> +
> +  reset-names:
> +    const: larb
> +
>   required:
>     - compatible
>     - reg
> @@ -125,6 +131,20 @@ allOf:
>         required:
>           - mediatek,larb-id
> 
> +  - if:  # only for image, camera and ipe subsys
> +      properties:
> +        compatible:
> +          const: mediatek,mt8188-smi-larb
> +        mediatek,larb-id:
> +          oneOf:

Are you really sure that you need 'oneOf' here? :-)

Regards,
Angelo

> +            - enum:
> +                [ 9, 10, 11, 12, 13, 16, 17, 18, 19, 20 ]
> +
> +    then:
> +      required:
> +        - resets
> +        - reset-names
> +
>   additionalProperties: false
> 
>   examples:
> --
> 2.46.0
>