[PATCH RFC] ARM: dts: bcm2711: Fix DMA constrains for newer BCM2711 boards

[Stefan Wahren]

The commit 3d2cbb644836 ("ARM: dts: bcm2711: Move emmc2 into its own bus")
assumed that all bootloader pass the FDT modified by the firmware to the
kernel. But this is not always the case (e.g. Fedora) and cause boot
issues for boards with a BCM2711 C0 SoC (RPi 400, CM4, newer RPi 4 B)
which does have different DMA constraints.

Since we are not able to detect the SoC revision, let's assume a BCM2711
C0 SoC for bcm2711.dtsi and move the restricted DMA constrains to a
separate RPi 4 B board file just for the old SoC revision.

Fixes: 3d2cbb644836 ("ARM: dts: bcm2711: Move emmc2 into its own bus")
Signed-off-by: Stefan Wahren <stefan.wahren at i2se.com>
---
 arch/arm/boot/dts/Makefile               |  1 +
 arch/arm/boot/dts/bcm2711-rpi-4-b-b0.dts | 22 ++++++++++++++++++++++
 arch/arm/boot/dts/bcm2711.dtsi           | 11 +++--------
 3 files changed, 26 insertions(+), 8 deletions(-)
 create mode 100644 arch/arm/boot/dts/bcm2711-rpi-4-b-b0.dts

diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
index 7c16f8a2b738..560d36ba1041 100644
--- a/arch/arm/boot/dts/Makefile
+++ b/arch/arm/boot/dts/Makefile
@@ -96,6 +96,7 @@ dtb-$(CONFIG_ARCH_BCM2835) += \
 	bcm2837-rpi-zero-2-w.dtb \
 	bcm2711-rpi-400.dtb \
 	bcm2711-rpi-4-b.dtb \
+	bcm2711-rpi-4-b-b0.dtb \
 	bcm2711-rpi-cm4-io.dtb \
 	bcm2835-rpi-zero.dtb \
 	bcm2835-rpi-zero-w.dtb
diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b-b0.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b-b0.dts
new file mode 100644
index 000000000000..c53ed510392f
--- /dev/null
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b-b0.dts
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+#include "bcm2711-rpi-4-b.dts"
+
+&emmc2bus {
+	/*
+	 * emmc2 on initial SoC revision (only assembled on RPi 4 B)
+	 * has different DMA constraints.
+	 */
+	dma-ranges = <0x0 0xc0000000  0x0 0x00000000  0x40000000>;
+};
+
+&pcie0 {
+	/*
+	 * The wrapper around the PCIe block has a bug
+	 * preventing it from accessing beyond the first 3GB of
+	 * memory.
+	 */
+	dma-ranges = <0x02000000 0x0 0x00000000 0x0 0x00000000
+				      0x0 0xc0000000>;
+};
+
diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
index 89af57482bc8..c307c45385a0 100644
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -420,7 +420,7 @@ emmc2bus: emmc2bus {
 		#size-cells = <1>;
 
 		ranges = <0x0 0x7e000000  0x0 0xfe000000  0x01800000>;
-		dma-ranges = <0x0 0xc0000000  0x0 0x00000000  0x40000000>;
+		dma-ranges = <0x0 0x00000000  0x0 0x00000000  0xfc000000>;
 
 		emmc2: mmc at 7e340000 {
 			compatible = "brcm,bcm2711-emmc2";
@@ -574,13 +574,8 @@ IRQ_TYPE_LEVEL_HIGH>,
 
 			ranges = <0x02000000 0x0 0xf8000000 0x6 0x00000000
 				  0x0 0x04000000>;
-			/*
-			 * The wrapper around the PCIe block has a bug
-			 * preventing it from accessing beyond the first 3GB of
-			 * memory.
-			 */
-			dma-ranges = <0x02000000 0x0 0x00000000 0x0 0x00000000
-				      0x0 0xc0000000>;
+			dma-ranges = <0x02000000 0x4 0x00000000 0x0 0x00000000
+				      0x1 0x00000000>;
 			brcm,enable-ssc;
 		};
 
-- 
2.25.1