linux-kernel - Re: [PATCH v2 1/1] dt-bindings: dmaengine: Add MediaTek Command-Queue DMA controller bindings

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Date:   Thu, 14 Feb 2019 10:18:52 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     shun-chih.yu@...iatek.com, Sean Wang <sean.wang@...iatek.com>,
        Vinod Koul <vkoul@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, srv_wsdupstream@...iatek.com
Subject: Re: [PATCH v2 1/1] dt-bindings: dmaengine: Add MediaTek Command-Queue
 DMA controller bindings



On 14/02/2019 08:54, shun-chih.yu@...iatek.com wrote:
> From: Shun-Chih Yu <shun-chih.yu@...iatek.com>
> 
> Document the devicetree bindings for MediaTek Command-Queue DMA controller
> which could be found on MT6765 SoC or other similar Mediatek SoCs.
> 
> Signed-off-by: Shun-Chih Yu <shun-chih.yu@...iatek.com>
> Reviewed-by: Rob Herring <robh@...nel.org>
> Acked-by: Sean Wang <sean.wang@...nel.org>
> ---
>  .../devicetree/bindings/dma/mtk-cqdma.txt          |   31 ++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/mtk-cqdma.txt
> 
> diff --git a/Documentation/devicetree/bindings/dma/mtk-cqdma.txt b/Documentation/devicetree/bindings/dma/mtk-cqdma.txt
> new file mode 100644
> index 0000000..fb12927
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/mtk-cqdma.txt
> @@ -0,0 +1,31 @@
> +MediaTek Command-Queue DMA Controller
> +==================================
> +
> +Required properties:
> +
> +- compatible:	Must be "mediatek,mt6765-cqdma" for MT6765.
> +- reg:		Should contain the base address and length for each channel.
> +- interrupts:	Should contain references to the interrupts for each channel.
> +- clocks:	Should be the clock specifiers corresponding to the entry in
> +		clock-names property.
> +- clock-names:	Should contain "cqdma" entries.

entries -> entry. There is only one clock

> +- dma-channels: The number of DMA channels supported by the controller.
> +- dma-requests: The number of DMA request supported by the controller.

The driver handles these as optional and uses MTK_CQDMA_NR_VCHANS and
MTK_CQDMA_NR_PCHANS in case the property is not present.

> +- #dma-cells: 	The length of the DMA specifier, must be <1>. This one cell
> +		in dmas property of a client device represents the channel
> +		number.
> +Example:
> +
> +        cqdma: dma-controller@...12000 {
> +		compatible = "mediatek,mt6765-cqdma";
> +		reg = <0 0x10212000 0 0x1000>;

Does this mean that you have to resources at base = 0x0 with different length?

Regards,
Matthias

> +		interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_LOW>,
> +			<GIC_SPI 114 IRQ_TYPE_LEVEL_LOW>;
> +		clocks = <&infracfg CLK_IFR_CQ_DMA>;
> +		clock-names = "cqdma";
> +		dma-channels = <2>;
> +		dma-requests = <32>;
> +		#dma-cells = <1>;
> +	};
> +
> +DMA clients must use the format described in dma/dma.txt file.
>