raspberry-pi: fix DTB name mapping for U-Boot compatibility

- Gate DTB copies on rpiVersion instead of host architecture, skipping
  the workaround entirely for Pi 4+ where vendor and upstream names match
- Fix bcm2835-rpi-zero.dtb: was incorrectly sourced from bcm2708-rpi-b-plus
  (overwriting an earlier copy from bcm2708-rpi-zero-w); now uses the
  correct bcm2708-rpi-zero.dtb
- Remove unused bcm2711-rpi-4-b.dtb -> bcm2838-rpi-4-b.dtb copy: U-Boot
  already uses bcm2711-rpi-4-b.dtb which the vendor kernel provides, and
  nothing references bcm2838-*

See: https://github.com/u-boot/u-boot/blob/master/board/raspberrypi/rpi/rpi.c

Author: JamieMagee

raspberry-pi/common/kernel.nix

@@ -97,17 +97,36 @@ lib.overrideDerivation
     ''
     +
       lib.optionalString
-        (lib.elem stdenv.hostPlatform.system [
-          "armv7l-linux"
-          "aarch64-linux"
-        ])
-        ''
-          copyDTB bcm2710-rpi-zero-2.dtb bcm2837-rpi-zero-2.dtb
-          copyDTB bcm2710-rpi-zero-2-w.dtb bcm2837-rpi-zero-2-w.dtb
-          copyDTB bcm2710-rpi-3-b.dtb bcm2837-rpi-3-b.dtb
-          copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-a-plus.dtb
-          copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-b-plus.dtb
-          copyDTB bcm2710-rpi-cm3.dtb bcm2837-rpi-cm3.dtb
-          copyDTB bcm2711-rpi-4-b.dtb bcm2838-rpi-4-b.dtb
-        '';
-  })
+      The vendor kernel uses different DTB names (bcm2708/bcm2709/bcm2710) than what
+    # U-Boot expects (bcm2835/bcm2836/bcm2837). Starting with Pi 4, names match.
+    # See: https://github.com/u-boot/u-boot/blob/master/board/raspberrypi/rpi/rpi.c
+    postFixup = lib.optionalString (rpiVersion < 4) (
+      ''
+        dtbDir=${if stdenv.hostPlatform.isAarch64 then "$out/dtbs/broadcom" else "$out/dtbs"}
+        rm $dtbDir/bcm283*.dtb
+        copyDTB() {
+          cp -v "$dtbDir/$1" "$dtbDir/$2"
+        }
+      ''
+      + lib.optionalString (rpiVersion == 1) ''
+        copyDTB bcm2708-rpi-zero.dtb bcm2835-rpi-zero.dtb
+        copyDTB bcm2708-rpi-zero-w.dtb bcm2835-rpi-zero-w.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-a.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b.dtb
+        copyDTB bcm2708-rpi-b.dtb bcm2835-rpi-b-rev2.dtb
+        copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-a-plus.dtb
+        copyDTB bcm2708-rpi-b-plus.dtb bcm2835-rpi-b-plus.dtb
+        copyDTB bcm2708-rpi-cm.dtb bcm2835-rpi-cm.dtb
+      ''
+      + lib.optionalString (rpiVersion == 2) ''
+        copyDTB bcm2709-rpi-2-b.dtb bcm2836-rpi-2-b.dtb
+      ''
+      + lib.optionalString (rpiVersion == 3) ''
+        copyDTB bcm2710-rpi-zero-2.dtb bcm2837-rpi-zero-2.dtb
+        copyDTB bcm2710-rpi-zero-2-w.dtb bcm2837-rpi-zero-2-w.dtb
+        copyDTB bcm2710-rpi-3-b.dtb bcm2837-rpi-3-b.dtb
+        copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-a-plus.dtb
+        copyDTB bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-b-plus.dtb
+        copyDTB bcm2710-rpi-cm3.dtb bcm2837-rpi-cm3.dtb
+      ''
+    )