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

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Message-ID: <e5627a69-c9e3-4966-89ce-5d8dd72df31a@collabora.com>
Date: Mon, 24 Feb 2025 09:42:15 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Friday Yang <friday.yang@...iatek.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>,
 Garmin Chang <garmin.chang@...iatek.com>, Yong Wu <yong.wu@...iatek.com>
Cc: linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org,
 Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v4 1/2] dt-bindings: clock: mediatek: Add SMI LARBs reset
 for MT8188

Il 21/02/25 08:50, Friday Yang ha scritto:
> 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 add '#reset-cells' for the clock controller located in image,
> camera and IPE subsystems.
> 
> Signed-off-by: Friday Yang <friday.yang@...iatek.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

> ---
>   .../bindings/clock/mediatek,mt8188-clock.yaml | 21 +++++++++++++++++++
>   1 file changed, 21 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/clock/mediatek,mt8188-clock.yaml b/Documentation/devicetree/bindings/clock/mediatek,mt8188-clock.yaml
> index 860570320545..2985c8c717d7 100644
> --- a/Documentation/devicetree/bindings/clock/mediatek,mt8188-clock.yaml
> +++ b/Documentation/devicetree/bindings/clock/mediatek,mt8188-clock.yaml
> @@ -57,6 +57,27 @@ required:
>     - reg
>     - '#clock-cells'
> 
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - mediatek,mt8188-camsys-rawa
> +              - mediatek,mt8188-camsys-rawb
> +              - mediatek,mt8188-camsys-yuva
> +              - mediatek,mt8188-camsys-yuvb
> +              - mediatek,mt8188-imgsys-wpe1
> +              - mediatek,mt8188-imgsys-wpe2
> +              - mediatek,mt8188-imgsys-wpe3
> +              - mediatek,mt8188-imgsys1-dip-nr
> +              - mediatek,mt8188-imgsys1-dip-top
> +              - mediatek,mt8188-ipesys
> +
> +    then:
> +      required:
> +        - '#reset-cells'
> +
>   additionalProperties: false
> 
>   examples:
> --
> 2.46.0
> 


-- 
AngeloGioacchino Del Regno
Senior Software Engineer

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