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>
---
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;
+ };
+ };
+
leds {
act {
gpios = <&gpio 42 GPIO_ACTIVE_HIGH>;
--
2.23.0
