From f169f60575bec7c61626af180cae364d321b4bec Mon Sep 17 00:00:00 2001
From: Florian Friesdorf <flo@chaoflow.net>
Date: Thu, 12 Jan 2012 07:54:09 +0000
Subject: [PATCH] powerManagement.enable sets link_power_management_policy to
 min_power

svn path=/nixos/trunk/; revision=31490
---
 modules/config/power-management.nix          |  2 +-
 modules/module-list.nix                      |  1 +
 modules/tasks/scsi-link-power-management.nix | 44 ++++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 modules/tasks/scsi-link-power-management.nix

diff --git a/modules/config/power-management.nix b/modules/config/power-management.nix
index 10aa821964a..7497877981c 100644
--- a/modules/config/power-management.nix
+++ b/modules/config/power-management.nix
@@ -92,7 +92,7 @@ in
       ];
 
     powerManagement.cpuFreqGovernor = "ondemand";
-
+    powerManagement.scsiLinkPolicy = "min_power";
   };
 
 }
diff --git a/modules/module-list.nix b/modules/module-list.nix
index 80f52be37f3..6c8159d1c42 100644
--- a/modules/module-list.nix
+++ b/modules/module-list.nix
@@ -195,6 +195,7 @@
   ./tasks/kbd.nix
   ./tasks/lvm.nix
   ./tasks/network-interfaces.nix
+  ./tasks/scsi-link-power-management.nix
   ./tasks/swraid.nix
   ./tasks/tty-backgrounds.nix
   ./virtualisation/libvirtd.nix
diff --git a/modules/tasks/scsi-link-power-management.nix b/modules/tasks/scsi-link-power-management.nix
new file mode 100644
index 00000000000..5ad04281509
--- /dev/null
+++ b/modules/tasks/scsi-link-power-management.nix
@@ -0,0 +1,44 @@
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+{
+  ###### interface
+
+  options = {
+  
+    powerManagement.scsiLinkPolicy = mkOption {
+      default = "";
+      example = "min_power";
+      description = ''
+        Configure the scsi link power management policy. By default,
+        the kernel configures "max_performance".
+      '';
+    };
+    
+  };
+
+
+  ###### implementation
+
+  config = mkIf (config.powerManagement.scsiLinkPolicy != "") {
+
+    environment.systemPackages = [ pkgs.cpufrequtils ];
+
+    jobs.cpufreq =
+      { description = "Set SCSI link power management policy";
+
+        startOn = "started udev";
+
+        task = true;
+
+        script = ''
+          for x in /sys/class/scsi_host/host*/link_power_management_policy; do
+            echo ${config.powerManagement.scsiLinkPolicy} > $x
+          done
+        '';
+      };
+      
+  };
+
+}