ARM: dts: bcm2711: force CMA into first GB of memory

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@suse.de>
Acked-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
index ac83dac..34d24fe 100644 (file)
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -12,6 +12,26 @@
 
        interrupt-parent = <&gicv2>;
 
+       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 BCM2711 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;
+               };
+       };
+
+
        soc {
                /*
                 * Defined ranges: