linux-kernel - Re: [PATCH v2 2/8] dt-bindings: i2c: qcom,i2c-geni: Add support for selecting data transfer mode

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Message-ID: <r4zfoaub3dwkirdbsolbl56xxa7ax5eusb2256c7ezlyl2s3vh@hit4g5cpzijw>
Date: Fri, 24 Jan 2025 13:18:00 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Viken Dadhaniya <quic_vdadhani@...cinc.com>
Cc: andi.shyti@...nel.org, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, gregkh@...uxfoundation.org, jirislaby@...nel.org, 
	broonie@...nel.or, andersson@...nel.org, konradybcio@...nel.org, 
	johan+linaro@...nel.org, dianders@...omium.org, agross@...nel.org, 
	linux-arm-msm@...r.kernel.org, linux-i2c@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, linux-spi@...r.kernel.org, 
	quic_msavaliy@...cinc.com, quic_anupkulk@...cinc.com
Subject: Re: [PATCH v2 2/8] dt-bindings: i2c: qcom,i2c-geni: Add support for
 selecting data transfer mode

On Fri, Jan 24, 2025 at 04:23:03PM +0530, Viken Dadhaniya wrote:
> Data transfer mode is fixed by TrustZone (TZ), which currently restricts
> developers from modifying the transfer mode from the APPS side.
> 
> Document the 'qcom,xfer-mode' properties to select the data transfer mode,
> either GPI DMA (Generic Packet Interface) or non-GPI mode (PIO/CPU DMA).
> 
> I2C controller can operate in one of two modes based on the
> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.

Is it possible to load the firmware after it being loaded by TZ? Is it
possible to change the mode at runtime too?

> 
> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
> Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
> ---
> 
> v1 -> v2:
> 
> - Drop 'qcom,load-firmware' property and add 'firmware-name' property in
>   qup common driver.
> - Update commit log.
> 
> v1 Link: https://lore.kernel.org/linux-kernel/20241204150326.1470749-2-quic_vdadhani@quicinc.com/
> ---
> ---
>  .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml        | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> index 9f66a3bb1f80..68e4bf0c84d1 100644
> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> @@ -66,6 +66,12 @@ properties:
>    required-opps:
>      maxItems: 1
>  
> +  qcom,xfer-mode:
> +    description: Set the value to 1 for non-GPI (FIFO/CPU DMA) mode and 3 for GPI DMA mode.
> +      The default mode is FIFO.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [1, 3]
> +
>  required:
>    - compatible
>    - interrupts
> @@ -142,5 +148,6 @@ examples:
>          interconnect-names = "qup-core", "qup-config", "qup-memory";
>          power-domains = <&rpmhpd SC7180_CX>;
>          required-opps = <&rpmhpd_opp_low_svs>;
> +        qcom,xfer-mode = <1>;

What does <1> mean? Please provide corresponding defines.

>      };
>  ...
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry