SPECULATIVE: moby: build kernel with MFD_RK8XXX_* as a module instead of as builtin

hosts/modules/hal/pine64-pinephone-pro/default.nix

@@ -128,6 +128,10 @@ in
       "rockchip_rga"
       "rockchip_vdec"
       "rockchipdrm"
+      # speculatively, might not need!
+      "rk8xx-core"
+      "rk8xx-i2c"
+      "rk8xx-spi"
 
       # these can surely be reduced:
       # "8250_dw"

pkgs/additional/linux-sane-pinephonepro/default.nix

@@ -375,5 +375,17 @@ linux_latest.override {
     #     INFINIBAND = lib.mkForce no;
     #   };
     # }
+    {
+      # i'd like to patch some drivers, and that's easier to do when i build them for out-of-tree.
+      name = "make-module-for-out-of-tree";
+      patch = null;
+      extraStructuredConfig = with lib.kernel; {
+        # MFD_CORE = module;
+        # MFD_ALTERA_SYSMGR = module;
+        MFD_RK8XX = module;
+        MFD_RK8XX_I2C = module;
+        MFD_RK8XX_SPI = module;  #< necessary for MFD_RK8XX=m to apply
+      };
+    }
   ];
 }