linux-kernel - Re: [PATCH v1 1/5] dt-bindings: dmaengine: qcom: gpi: Add additional arg to dma-cell property

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Message-ID: <20241015140108.GA620512-robh@kernel.org>
Date: Tue, 15 Oct 2024 09:01:08 -0500
From: Rob Herring <robh@...nel.org>
To: Jyothi Kumar Seerapu <quic_jseerapu@...cinc.com>
Cc: Vinod Koul <vkoul@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Andi Shyti <andi.shyti@...nel.org>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Christian König <christian.koenig@....com>,
	cros-qcom-dts-watchers@...omium.org, linux-arm-msm@...r.kernel.org,
	dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linaro-mm-sig@...ts.linaro.org, quic_msavaliy@...cinc.com,
	quic_vtanuku@...cinc.com
Subject: Re: [PATCH v1 1/5] dt-bindings: dmaengine: qcom: gpi: Add additional
 arg to dma-cell property

On Tue, Oct 15, 2024 at 05:37:46PM +0530, Jyothi Kumar Seerapu wrote:
> When high performance with multiple i2c messages in a single transfer
> is required, employ Block Event Interrupt (BEI) to trigger interrupts
> after specific messages transfer and the last message transfer,
> thereby reducing interrupts.
> 
> For each i2c message transfer, a series of Transfer Request Elements(TREs)
> must be programmed, including config tre for frequency configuration,
> go tre for holding i2c address and dma tre for holding dma buffer address,
> length as per the hardware programming guide. For transfer using BEI,
> multiple I2C messages may necessitate the preparation of config, go,
> and tx DMA TREs. However, a channel TRE size of 64 is often insufficient,
> potentially leading to failures due to inadequate memory space.
> 
> Add additional argument to dma-cell property for channel TRE size.

No such property 'dma-cell'

> With this, adjust the channel TRE size via the device tree.
> The default size is 64, but clients can modify this value based on
> their specific requirements.
> 
> Signed-off-by: Jyothi Kumar Seerapu <quic_jseerapu@...cinc.com>
> ---
>  Documentation/devicetree/bindings/dma/qcom,gpi.yaml | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/dma/qcom,gpi.yaml b/Documentation/devicetree/bindings/dma/qcom,gpi.yaml
> index 4df4e61895d2..002495921643 100644
> --- a/Documentation/devicetree/bindings/dma/qcom,gpi.yaml
> +++ b/Documentation/devicetree/bindings/dma/qcom,gpi.yaml
> @@ -54,14 +54,16 @@ properties:
>      maxItems: 13
>  
>    "#dma-cells":
> -    const: 3
> +    minItems: 3
> +    maxItems: 4
>      description: >
>        DMA clients must use the format described in dma.txt, giving a phandle
> -      to the DMA controller plus the following 3 integer cells:
> +      to the DMA controller plus the following 4 integer cells:
>        - channel: if set to 0xffffffff, any available channel will be allocated
>          for the client. Otherwise, the exact channel specified will be used.
>        - seid: serial id of the client as defined in the SoC documentation.
>        - client: type of the client as defined in dt-bindings/dma/qcom-gpi.h
> +      - channel-tre-size: size of the channel TRE (transfer ring element)
>  
>    iommus:
>      maxItems: 1
> -- 
> 2.17.1
>