Re: [PATCH 1/2] ARM: dts: bcm2711: force CMA into first GB of memory

[Stefan Wahren]

Hi Nicolas,

Am 04.11.19 um 14:54 schrieb Nicolas Saenz Julienne:
> arm64 places the CMA in ZONE_DMA32, which is not good enough for the
> Raspberry Pi 4 since it contains peripherals that can only address the
> first GB of memory. Explicitly place the CMA into that area.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>

do you want this in Linux 5.5 via devicetree/fixes? In this case please
add an fixes tag.

Otherwise this will be queued for Linux 5.6.

> ---
>  arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> index cccc1ccd19be..3c7833e9005a 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> @@ -19,6 +19,25 @@
>  		reg = <0 0 0>;
>  	};
>
> +	reserved-memory {
> +		#address-cells = <2>;
> +		#size-cells = <1>;
> +		ranges;
> +
> +		/*
> +		 * arm64 reserves the CMA by default somewhere in ZONE_DMA32,
> +		 * that's not good enough for the Raspberry Pi 4 as some
> +		 * devices can only address the lower 1G of memory (ZONE_DMA).
> +		 */
> +		linux,cma {
> +			compatible = "shared-dma-pool";
> +			size = <0x2000000>; /* 32MB */
> +			alloc-ranges = <0x0 0x00000000 0x40000000>;
> +			reusable;
> +			linux,cma-default;
> +		};
> +	};
> +

i think this is a SoC-specific issue not a board specifc one. Please
move this to bcm2711.dtsi

Thanks
Stefan

>  	leds {
>  		act {
>  			gpios = <&gpio 42 GPIO_ACTIVE_HIGH>;