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Subject[PATCH] ARM: dts: bcm283x: Unify CMA configuration
Date
With the introduction of the Raspberry Pi 4 we were forced to explicitly
configure CMA's location, since arm64 defaults it into the ZONE_DMA32
memory area, which is not good enough to perform DMA operations on that
device. To bypass this limitation a dedicated CMA DT node was created,
explicitly indicating the acceptable memory range and size.

That said, compatibility between boards is a must on the Raspberry Pi
ecosystem so this creates a common CMA DT node so as for DT overlays to
be able to update CMA's properties regardless of the board being used.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---

If this doesn't make it into v5.5 I'd be tempted to add:
Fixes: d98a8dbdaec6 ("ARM: dts: bcm2711: force CMA into first GB of memory")

arch/arm/boot/dts/bcm2711.dtsi | 33 +++++++++++++--------------------
arch/arm/boot/dts/bcm283x.dtsi | 13 +++++++++++++
2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
index 8687534d4528..c8e4041308e0 100644
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -12,26 +12,6 @@ / {

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:
@@ -869,6 +849,19 @@ pin-rts {
};
};

+&rmem {
+ #address-cells = <2>;
+};
+
+&cma {
+ /*
+ * 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).
+ */
+ alloc-ranges = <0x0 0x00000000 0x40000000>;
+};
+
&i2c0 {
compatible = "brcm,bcm2711-i2c", "brcm,bcm2835-i2c";
interrupts = <GIC_SPI 117 IRQ_TYPE_LEVEL_HIGH>;
diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
index 839491628e87..6128baed83c2 100644
--- a/arch/arm/boot/dts/bcm283x.dtsi
+++ b/arch/arm/boot/dts/bcm283x.dtsi
@@ -30,6 +30,19 @@ chosen {
stdout-path = "serial0:115200n8";
};

+ rmem: reserved-memory {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+
+ cma: linux,cma {
+ compatible = "shared-dma-pool";
+ size = <0x4000000>; /* 64MB */
+ reusable;
+ linux,cma-default;
+ };
+ };
+
thermal-zones {
cpu_thermal: cpu-thermal {
polling-delay-passive = <0>;
--
2.24.1
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