linux-kernel - Re: [PATCH v2 2/2] ARM: dts: stm32: Enable MIPI DSI display support.

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Date:   Tue, 21 Jul 2020 11:09:22 +0200
From:   Alexandre Torgue <alexandre.torgue@...com>
To:     Adrian Pop <pop.adrian61@...il.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>
CC:     <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] ARM: dts: stm32: Enable MIPI DSI display support.

Hi Adrian

On 7/2/20 7:27 PM, Adrian Pop wrote:
> STM32f769-disco features a 4" MIPI DSI display: add support for it.
> On Cortex-M7 DMA can't use cached memory. For this reason I use a dedicated
> memory pool for DMA with no-cache attribute which is located at the end of
>   RAM.
> 
> Signed-off-by: Adrian Pop <pop.adrian61@...il.com>
> ---
>   arch/arm/boot/dts/stm32f746.dtsi      | 34 +++++++++++++++++++
>   arch/arm/boot/dts/stm32f769-disco.dts | 49 +++++++++++++++++++++++++++
>   2 files changed, 83 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/stm32f746.dtsi b/arch/arm/boot/dts/stm32f746.dtsi
> index 93c063796780..577a812ca01c 100644
> --- a/arch/arm/boot/dts/stm32f746.dtsi
> +++ b/arch/arm/boot/dts/stm32f746.dtsi
> @@ -48,6 +48,19 @@ / {
>   	#address-cells = <1>;
>   	#size-cells = <1>;
>   
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,dma {
> +			compatible = "shared-dma-pool";
> +			linux,dma-default;
> +			no-map;
> +			reg = <0xc0f00000 0x100000>;
> +		};
> +	};
> +

Please check Rob's remark (make W=1). Furthermore this node should be 
declared in board dts file is should depend on SDRAM size embedded on board.

>   	clocks {
>   		clk_hse: clk-hse {
>   			#clock-cells = <0>;
> @@ -75,6 +88,27 @@ clk_i2s_ckin: clk-i2s-ckin {
>   	};
>   
>   	soc {
> +		ltdc: display-controller@...16800 {
> +			compatible = "st,stm32-ltdc";
> +			reg = <0x40016800 0x200>;
> +			interrupts = <88>, <89>;
> +			resets = <&rcc STM32F7_APB2_RESET(LTDC)>;
> +			clocks = <&rcc 1 CLK_LCD>;
> +			clock-names = "lcd";
> +			status = "disabled";
> +		};
> +
> +		dsi: dsi@...16c00 {
> +			compatible = "st,stm32-dsi";
> +			reg = <0x40016c00 0x800>;
> +			interrupts = <98>;
> +			clocks = <&rcc 1 CLK_F769_DSI>, <&clk_hse>;
> +			clock-names = "pclk", "ref";
> +			resets = <&rcc STM32F7_APB2_RESET(DSI)>;
> +			reset-names = "apb";
> +			status = "disabled";
> +		};
> +

Nodes are ordered by address in soc dtsi file. Please follow it.

>   		timer2: timer@...00000 {
>   			compatible = "st,stm32-timer";
>   			reg = <0x40000000 0x400>;
> diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
> index 1626e00bb2cb..a9e81b49809c 100644
> --- a/arch/arm/boot/dts/stm32f769-disco.dts
> +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> @@ -153,3 +153,52 @@ &usbotg_hs {
>   	pinctrl-names = "default";
>   	status = "okay";
>   };
> +
> +&dsi {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	status = "okay";
> +
> +	ports {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		port@0 {
> +			reg = <0>;
> +			dsi_in: endpoint {
> +				remote-endpoint = <&ltdc_out_dsi>;
> +			};
> +		};
> +
> +		port@1 {
> +			reg = <1>;
> +			dsi_out: endpoint {
> +				remote-endpoint = <&dsi_in_panel>;
> +			};
> +		};
> +
> +	};
> +
> +	panel: panel {
> +		compatible = "orisetech,otm8009a";
> +		reg = <0>;
> +		reset-gpios = <&gpioj 15 GPIO_ACTIVE_LOW>;
> +		status = "okay";
> +
> +		port {
> +			dsi_in_panel: endpoint {
> +				remote-endpoint = <&dsi_out>;
> +			};
> +		};
> +	};
> +};
> +
> +&ltdc {
> +	status = "okay";
> +
> +	port {
> +		ltdc_out_dsi: endpoint {
> +			remote-endpoint = <&dsi_in>;
> +		};
> +	};
> +};