Re: [PATCH v5 3/3] ARM: dts: stm32: support display on stm32f746-disco board

[Alexandre TORGUE <alexandre.torgue@foss.st.com>]

Hi Dario

On 6/29/23 10:37, Dario Binacchi wrote:
> Add support to Rocktech RK043FN48H display on stm32f746-disco board.
> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> 
> ---
> 
> Changes in v5:
> I am confident that framebuffer sizing is a real requirement for STM32 boards,
> but I need some time to understand if and how to introduce this functionality.
> Therefore, I drop the following patches to allow the series to be fully merged:
>   - [4/6] dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property
>   - [5/6] ARM: dts: stm32: set framebuffer bit depth on stm32f746-disco
>   - [6/6] drm/stm: set framebuffer bit depth through DTS property
> 
> Changes in v4:
> - Use DTS property instead of module parameter to set the framebuffer bit depth.
> 
> Changes in v3:
> - drop [4/6] dt-bindings: display: simple: add Rocktech RK043FN48H
>    Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-next):
>    https://cgit.freedesktop.org/drm/drm-misc/commit/?id=c42a37a27c777d63961dd634a30f7c887949491a
> - drop [5/6] drm/panel: simple: add support for Rocktech RK043FN48H panel
>    Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-next)
>    https://cgit.freedesktop.org/drm/drm-misc/commit/?id=13cdd12a9f934158f4ec817cf048fcb4384aa9dc
> 
>   arch/arm/boot/dts/stm32f746-disco.dts | 51 +++++++++++++++++++++++++++
>   1 file changed, 51 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/stm32f746-disco.dts b/arch/arm/boot/dts/stm32f746-disco.dts
> index c11616ed5fc6..cda423b6a874 100644
> --- a/arch/arm/boot/dts/stm32f746-disco.dts
> +++ b/arch/arm/boot/dts/stm32f746-disco.dts
> @@ -60,10 +60,41 @@ memory@c0000000 {
>   		reg = <0xC0000000 0x800000>;
>   	};
>   
> +	reserved-memory {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		linux,cma {
> +			compatible = "shared-dma-pool";
> +			no-map;
> +			size = <0x80000>;
> +			linux,dma-default;
> +		};
> +	};
> +
>   	aliases {
>   		serial0 = &usart1;
>   	};
>   
> +	backlight: backlight {
> +		compatible = "gpio-backlight";
> +		gpios = <&gpiok 3 GPIO_ACTIVE_HIGH>;
> +		status = "okay";
> +	};
> +
> +	panel_rgb: panel-rgb {
> +		compatible = "rocktech,rk043fn48h";
> +		backlight = <&backlight>;
> +		enable-gpios = <&gpioi 12 GPIO_ACTIVE_HIGH>;
> +		status = "okay";
> +		port {
> +			panel_in_rgb: endpoint {
> +				remote-endpoint = <&ltdc_out_rgb>;
> +			};
> +		};
> +	};
> +
>   	usbotg_hs_phy: usb-phy {
>   		#phy-cells = <0>;
>   		compatible = "usb-nop-xceiv";
> @@ -99,6 +130,26 @@ &i2c1 {
>   	status = "okay";
>   };
>   
> +&dma1 {
> +	status = "okay";
> +};
> +
> +&dma2 {
> +	status = "okay";
> 
Why do you enable DMAs ? It seems not used by LTDC.

> +&ltdc {
> +	pinctrl-0 = <&ltdc_pins_a>;
> +	pinctrl-names = "default";
> +	status = "okay";
> +
> +	port {
> +		ltdc_out_rgb: endpoint {
> +			remote-endpoint = <&panel_in_rgb>;
> +		};
> +	};
> +};
> +
>   &sdio1 {
>   	status = "okay";
>   	vmmc-supply = <&mmc_vcard>;