RE: [PATCH] arm64: dts: renesas: r8a77951: Add reserved memory region

[Biju Das]

> -----Original Message-----
> From: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
> Sent: 14 November 2022 19:49
> To: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Magnus Damm
> <magnus.damm@xxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof
> Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>; open list:ARM/RENESAS
> ARCHITECTURE <linux-renesas-soc@xxxxxxxxxxxxxxx>; open list:OPEN
> FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
> <devicetree@xxxxxxxxxxxxxxx>; Detlev Casanova
> <detlev.casanova@xxxxxxxxxxxxx>
> Subject: [PATCH] arm64: dts: renesas: r8a77951: Add reserved memory
> region
> 
> The 0x3000000 bytes memory region starting at 0x54000000 is reserved
> for the lossy_decompression hardware that will try to decompress any
> data written in the region.
> 
> Mark the region as no-map to prevent linux from using it as RAM.
> 
> Signed-off-by: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
> ---
>  arch/arm64/boot/dts/renesas/r8a77951.dtsi | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> b/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> index 07c8763c1e77..171833d91313 100644
> --- a/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> @@ -290,6 +290,18 @@ CPU_SLEEP_1: cpu-sleep-1 {
>  		};
>  	};
> 
> +	reserved-memory {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		/* device specific region for Lossy Decompression */
> +		lossy_decompress: memory-region@54000000 {
> +			no-map;
> +			reg = <0x00000000 0x54000000 0x0 0x03000000>;
> +		};
> +	};

Is not part of TFA[1]?

[1] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/renesas/rcar/bl2_plat_setup.c#n174

> +
>  	extal_clk: extal {
>  		compatible = "fixed-clock";
>  		#clock-cells = <0>;
> --
> 2.38.1