u-boot-pinephone-pro: tune UART & memory addresses

pkgs/additional/u-boot-pinephone-pro/default.nix

@@ -24,6 +24,29 @@
     "u-boot.sym"
   ];
 }).overrideAttrs (base: {
+  # default baud rate is 1500000, which is too fast for some USB <-> serial adapters to do
+  extraConfig = ''
+    CONFIG_BAUDRATE=115200
+  '';
+  # default layout is:
+  # scriptaddr         = 0x00500000
+  # script_offset_f    = 0xffe000
+  # script_size_f      = 0x2000
+  # pxefile_addr_r     = 0x00600000
+  # fdt_addr_r         = 0x01e00000
+  # fdtoverlay_addr_r  = 0x01f00000
+  # kernel_addr_r      = 0x02080000
+  # ramdisk_addr_r     = 0x06000000
+  # kernel_comp_addr_r = 0x08000000
+  # kernel_comp_size   = 0x2000000
+  #
+  # this offers 63.5 MiB for the kernel.
+  # unfortunately, my bloated kernels can be larger than that, so push the addresses back and hope it works:
+  postPatch = (base.postPatch or "") + ''
+    substituteInPlace include/configs/rk3399_common.h \
+      --replace-fail ramdisk_addr_r=0x06000000 ramdisk_addr_r=0x0a000000 \
+      --replace-fail kernel_comp_addr_r=0x08000000 kernel_comp_addr_r=0x0c000000
+  '';
   env = (base.env or {}) // {
     # XXX: RK3399 ships a blob for HDCP (media copy protection) in the trusted firmware.
     #      that can be removed with `unfreeIncludeHDCPBlob = false`, if so desired.