add p52

lenovo/thinkpad/p52/default.nix

@@ -0,0 +1,66 @@
+{ lib, ... }:
+{
+  imports = [
+    ../../../common/gpu/nvidia.nix
+    ../../../common/cpu/intel
+    ../../../common/pc/laptop/acpi_call.nix
+    ../.
+  ];
+
+  hardware = {
+    nvidia = {
+      prime = {
+        intelBusId = "PCI:0:2:0";
+        nvidiaBusId = "PCI:1:0:0";
+      };
+    };
+
+    # is this too much?  It's convenient for Steam.
+    opengl = {
+      driSupport = lib.mkDefault true;
+      driSupport32Bit = lib.mkDefault true;
+    };
+  };
+
+  # Sleep
+  # -----
+  #
+  # The system will not stay asleep properly while on battery power or AC in
+  # either offload mode or sync mode.  This is true whether TLP is enabled or
+  # disabled.  When the system is told to sleep, it will appear to go into a
+  # sleep state, but within five minutes (and sometimes much more quickly; in
+  # my case especially if a USB hub is connected), it will wake itself.  I
+  # attempted to identify what was causing this to happen, but was not
+  # successful.  Note that this behavior is different from that of the P50 or
+  # P51, both of which can be convinced to sleep by changing TLP config.
+  #
+  # throttled vs. thermald
+  # -----------------------
+  #
+  # NB: the p53 profile currently uses throttled to prevent too-eager CPU
+  # throttling.  I understand throttled to have been a workaround solution at
+  # the time the p53 profile was created (throttled's original name was
+  # "lenovo_fix").  thermald would have been preferred if it worked at the
+  # time.
+  #
+  # I read
+  # https://wiki.archlinux.org/title/Lenovo_ThinkPad_X1_Carbon_(Gen_6)#Power_management.2FThrottling_issues
+  # as saying that thermald is fixed under the circumstance that led to the
+  # development of throttled given version 5.12+ of the kernel combined
+  # with version 2.4.3+ of thermald.  At the time of this writing, the
+  # stable NixOS kernel is 5.15 and 2.4.9 of thermald.
+  #
+  # In the meantime, I also ran the "s-tui" program which can stress test the
+  # system, while eyeing up the core temps and CPU frequency under three
+  # scenarios: under thermald, under throttled, and with neither.  None of the
+  # scenarios seem to have massively improved fan behavior, core temps, or
+  # average CPU frequency than another.  The highest core temp always seems to
+  # hover around 90 degrees C, the lowest CPU Ghz around 3.4 on a 3.8Ghz machine.
+  #
+  # I ended up choosing throttled because subjectively, the fans seem quieter
+  # when it's stressed and it allows the average temps to get a degree or two
+  # higher when running throttled than when running in the other two scenarios,
+  # but still substantially under critical temp.
+
+  services.thermald.enable = lib.mkDefault true;
+}