Category:How to - Low Power - Revision history

Ashcharles: /* Relevant Community Mailing List Threads */

2016-04-01T21:31:24Z

‎Relevant Community Mailing List Threads

Maroc: /* Disable LEDs */ Updated for new kernel

2011-07-22T15:09:48Z

‎Disable LEDs: Updated for new kernel

Maroc: /* Wifi/Bluetooth */ Added instructions for disabling Wifi/Bluetooth

2011-07-22T15:07:49Z

‎Wifi/Bluetooth: Added instructions for disabling Wifi/Bluetooth

Maroc: Changed PM kernel to Steve's 2.6.39 kernel

2011-07-22T14:55:23Z

Changed PM kernel to Steve's 2.6.39 kernel

Show changes

Maroc: /* Disable Internal Devices */ Added note explaining peripherals are off while sleeping.

2011-03-17T13:58:15Z

‎Disable Internal Devices: Added note explaining peripherals are off while sleeping.

Maroc: Fix typo with "run loaduimage" command

2011-03-13T13:34:05Z

Fix typo with "run loaduimage" command

Maroc: /* USB */

2011-03-13T04:32:04Z

‎USB

Maroc: /* PM Features */ Clarified instructions for different kernels

2011-03-13T04:23:47Z

‎PM Features: Clarified instructions for different kernels

Maroc: /* Custom PM Kernel */ Rewrote a few sentences and added a note for usb off.

2011-03-13T04:12:25Z

‎Custom PM Kernel: Rewrote a few sentences and added a note for usb off.

Maroc: Changed to use bitbake recipe for 2.6.38 PM kernel

2011-03-11T23:33:28Z

Changed to use bitbake recipe for 2.6.38 PM kernel

@@ Line 3: / Line 3: @@
 ===Relevant Community Mailing List Threads===
-[http://old.nabble.com/sample-numbers-for-Overo-Earth-power-consumption-td29792431.html sample numbers for Overo Earth COM power consumption]
+[http://gumstix.8.x6.nabble.com/sample-numbers-for-Overo-Earth-power-consumption-td661334.html sample numbers for Overo Earth COM power consumption]
-[http://old.nabble.com/Building-a-linux-omap3-pm-for-Overo-td29819751.html#a29819751 Building a linux omap3 pm for Overo]
+[http://gumstix.8.x6.nabble.com/Building-a-linux-omap3-pm-for-Overo-td641140.html Building a linux omap3 pm for Overo]
-[http://old.nabble.com/cpufreq-on-the-Overo-td21680612.htm cpufreq on the Overo]
+[http://gumstix.8.x6.nabble.com/cpufreq-on-the-Overo-td593942.html cpufreq on the Overo]
 ==Background==

@@ Line 228: / Line 228: @@
   $ echo 1 > /sys/class/gpio/gpio211/value
-'''Note:''' Your kernel must be patched or you must be using the custom 2.6.38 PM kernel to access GPIO 211.
+'''Note:''' You must be running the 2.6.39 PM kernel to have access to GPIO 211.
-−
-−
-−
-−
 ==Legacy PM Kernels==

@@ Line 190: / Line 190: @@
   in the function "twl_probe" in /drivers/mfd/twl-core.c just prior to the comment "load power event scripts".
-===Wifi/Bluetooth===
+===Disable Wifi===
-If not using the combined Wifi/Bluetooth module, you can hold it in reset.  You can also hold it in reset and only enable as needed for periodic connectivity.
+To disable Wifi
-  TBD
+  $ echo 0 > /sys/class/gpio/gpio16/value
 ==Disable LEDs==

@@ Line 269: / Line 269: @@
 ==Disable Internal Devices==
 The internal peripherals and devices such as the DSP and GPU consume power if not being used. All unused peripherals, DSP, and GPU should be turned off.
 ===Turn Off Peripherals===

@@ Line 70: / Line 70: @@
   setenv console ttyO2,115200n8
   saveenv (run only if you want to save the new console setting)
-  run loaduImage
+  run loaduimage
   run mmcboot

@@ Line 288: / Line 288: @@
 ===USB===
-You can hold the USB chip in reset with the following commands:
+If you're running the Custom PM Kernel listed above, the kernel is already patched to disable power to USB. Otherwise, you can hold the USB chip in reset with the following commands:
   $ echo 183 > /sys/class/gpio/export
@@ Line 301: / Line 301: @@
          twl_i2c_write_u8(TWL4030_MODULE_USB, 0x08 /* value */, 0xBB /* register (CARKIT_ANA_CTRL) */);
          twl_i2c_write_u8(TWL4030_MODULE_USB, 0x01 /* value */, 0xFD /*register (PHY_PWR_CTRL) */);
   in the function "twl_probe" in /drivers/mfd/twl-core.c just prior to the comment "load power event scripts".
 ===Wifi/Bluetooth===

@@ Line 177: / Line 177: @@
 ===Setup Debug FS===
-If you are using a PM kernel higher than 2.6.29 or are using the stock 2.6.36 kernel with OpenEmbedded, then before you can enable PM features, you need to setup the debug file system for manipulating pm configuration.
+If you are using any kernel higher than 2.6.29 (PM or standard kernel), then before you can enable PM features, you need to setup the debug file system for manipulating pm configuration.
   mkdir /debug
   mount -t debugfs debugfs /debug
 ===Sleep While Idle===
 Next, enable "sleep while idle". This will allow the processor to attempt deeper sleep states when idle. You must also enable sleep timeouts for the serial ports, otherwise this will result in '''increased''' power consumption.
   # echo 5 > /sys/devices/platform/serial8250.0/sleep_timeout
   # echo 5 > /sys/devices/platform/serial8250.1/sleep_timeout
@@ Line 198: / Line 201: @@
 Dynamic frequency and voltage scaling dynamically reduces clock frequency and voltage for further power savings. You must be running the PM kernel for DVFS functionality.
-'''Note:''' DVFS only works with the 2.6.29 PM kernel.  Its technically not necessary since the sleep while idle and off modes reduce the frequency and voltage automatically.  DVFS is only needed if you don't won't to run a full speed and power when not idle.
+'''Note:''' DVFS only works with the 2.6.29 PM kernel (so far).  Its technically not necessary in newer kernels since the sleep while idle and off modes reduce the frequency and voltage automatically when idle.  DVFS is only needed if you don't won't to run at full speed and power when not idle.
 The cpufreq utils and daemon are needed to enable and configure DVFS. Use bitbake to manually build cpufreqd and cpufrequtils.
@@ Line 205: / Line 208: @@
   $ bitbake cpufrequtils
-You can also place these dependencies in your user config recipie....TODO
+'''Note:''' You can also copy the omap3-console-image.bb recipe over to your user.collection and add cpufreqd and cpufrequtils to the recipe.  Doing so will automatically include the cpufreqd and cpufrequtils in your image.
 Once the cpufreqd and cpufrequtils are built, you can build your image as normal, or you can simply copy the ipk files to your SD card and install them.

@@ Line 42: / Line 42: @@
 ===Custom PM Kernel===
-If you already have an open embedded build system setup, then follow the directions in this section for the easiest and quickest build.
+The "custom" PM kernel described here uses the 2.6.38-rc? PM kernel which at the time of this writing offers the best power saving features.
 First download the custom PM recipes from [http://iconux.org/files/oe/user.collection_overo_pm.tar.gz here] and extract the archive to your over-oe directory.
@@ Line 49: / Line 49: @@
 Bitbake the new kernel and make sure it builds correctly.
   $ bitbake -b user.collection/recipes/linux/linux-omap-pm_2.6.38.bb
 Or simply run
@@ Line 59: / Line 62: @@
   $ bitbake omap3-console-image
-Once you install the new build to your micro sd card, you'll need to make some changes for the new kernel. The new kernel uses ttyO2 as the serial port instead of ttyS2. So you need to make changes in your ext3 file system. cd to the os partition on your micro sd card (from your development system) and do the following.
+Once you install the new build to your micro sd card, you need to make changes for the new kernel. The new kernel uses ttyO2 as the serial port instead of ttyS2. To make the changes,cd to the Gumstix os partition on your micro sd, and do the following:
 * Edit <path to mcirosd rootfs>/etc/inittab and change ttyS2 to ttyO2
 * Make a "node" in dev for ttyO2
@@ Line 66: / Line 69: @@
   mmc init
   setenv console ttyO2,115200n8
   run loaduImage
   run mmcboot

@@ Line 21: / Line 21: @@
 The [http://elinux.org/OMAP_Power_Management PM kernel] is a development branch of the linux-omap kernel focused on developing the power management features of OMAP.  By default, openembedded does not use the PM kernel, but instead uses the mainstream linux-omap kernel. Some of the changes of the PM branch have been merged to the mainstream linux-omap branch.  However, not all changes have been merged so you must manually configure openembedded to use the PM kernel to get the most power savings possible.
-===Compile PM Kernel===
+There are three methods for compiling a PM kernel.
-'''NOTE:'''  The linux-omap-pm bitbake recipe is setup to use the 2.6.29 PM kernel.  Even though this kernel is significantly older than the mainstream 2.6.36 linux-omap kernel, it is necessary to use a PM kernel to get all PM features such as DVFS.  In fact, the most savings will be seen with the most recent PM kernel.  See the two alternate methods below for instructions on how to use the latest PM kernel.
+* Use the PM recipe included with the current OpenEmbedded build.
-'''TODO:'''  Update bitbake recipe for latest PM branch.
+===OpenEmbedded PM Kernel===
 To enable the PM kernel edit the file
@@ Line 38: / Line 41: @@
 Once you have the PM kernel built, follow the instructions for copying the new image and filesystem to your microSD card.
-===PM Kernel Alternate OpenEmbedded Method===
+===Custom PM Kernel===
 If you already have an open embedded build system setup, then follow the directions in this section for the easiest and quickest build.
-First git the sources for the pm kernel branch
+First download the custom PM recipes from [http://iconux.org/files/oe/user.collection_overo_pm.tar.gz here] and extract the archive to your over-oe directory.
- $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap-pm.git;branch=pm
-and cd into the resulting "linux-omap-pm" directory.
-'''NOTE:''' This will pull the latest development code from the pm kernel branch.  Since this code is in constant development, things can change quickly.
+'''Note:'''  If you have an existing user.collection in your overo-oe directory, you may want to back it up before extracting this archive.
-'''TODO:''' Change to have git pull a known working revision.
+Bitbake the new kernel and make sure it builds correctly.
-Add the openembedded cross compile tools to your path.
+You may get an error saying it can't download the tar archive but it should fallback to pulling the source using git.  This step will take a while since the pm git is over 400 MB.
- $ PATH=<path to oe tmp>/sysroots/i686-linux/usr/armv7a/bin/:<path to oe tmp>/sysroots/i686-linux/usr/bin:$PATH
-Next, activate the default config for omap2 and higher devices.
- $ make CROSS_COMPILE=arm-angstrom-linux-gnueabi- ARCH=arm omap2plus_defconfig
-By default, this config does not have the cpu frequency scaling enabled.  In order to enable it you need to edit the config.
-  $ make menuconfig
-Navigate to CPU Power Management and enable "CPU Frequency Scaling".  Exit the config and select yes to save it.
-Finally, build the kernel image.
+If the kernel builds fine, you can build your image normally.
-  $ make CROSS_COMPILE=arm-angstrom-linux-gnueabi- ARCH=arm uImage
+  $ bitbake omap3-console-image
-−
-Copy the resulting image to the FAT partition of your microSD card.  The image can be found at
- ./arch/arm/boot/uImage
-−
-You can now follow steps 4 through 6 in the CodeSourcery method below or continue here.
-The new kernel uses ttyO2 as the serial port instead of ttyS2. So you need to make changes in your ext3 file system. cd to the os partition on your micro sd card (from your development system) and do the following.
+Once you install the new build to your micro sd card, you'll need to make some changes for the new kernel. The new kernel uses ttyO2 as the serial port instead of ttyS2. So you need to make changes in your ext3 file system. cd to the os partition on your micro sd card (from your development system) and do the following.
 * Edit <path to mcirosd rootfs>/etc/inittab and change ttyS2 to ttyO2
 * Make a "node" in dev for ttyO2
@@ Line 83: / Line 77: @@
 If you do not already have an openembedded build setup, then follow these step taken from Peter Lawrence on the Gumstix mailing list.
-'''NOTE:'''  As per the comments below, this method disables nand and microSD access.
+'''NOTE:'''  As per the comments below, this method disables nand and microSD access. Use the Custom PM method above for best results.
-−
-'''TODO:'''  See how to get nand and microSD working with the latest PM kernel.
   <pre>
@@ Line 181: / Line 173: @@
 ===Setup Debug FS===
-If you are using a non PM kernel, then before you can enable PM features, you need to setup the debug file system for manipulating pm configuration.
+If you are using a PM kernel higher than 2.6.29 or are using the stock 2.6.36 kernel with OpenEmbedded, then before you can enable PM features, you need to setup the debug file system for manipulating pm configuration.
   mkdir /debug
   mount -t debugfs debugfs /debug
@@ Line 191: / Line 183: @@
   # echo 5 > /sys/devices/platform/serial8250.1/sleep_timeout
   # echo 5 > /sys/devices/platform/serial8250.2/sleep_timeout
-  # echo 1 > /sys/power/sleep_while_idle
+  # echo 1 > /debug/pm_debug/sleep_while_idle
 You can also enable "off mode" after enabling "sleep while idle".
-  # echo 1 > /sys/power/enable_off_mode
+  # echo 1 > /debug/pm_debug/enable_off_mode
@@ Line 201: / Line 193: @@
 ===DVFS===
 Dynamic frequency and voltage scaling dynamically reduces clock frequency and voltage for further power savings. You must be running the PM kernel for DVFS functionality.
 The cpufreq utils and daemon are needed to enable and configure DVFS. Use bitbake to manually build cpufreqd and cpufrequtils.
@@ Line 313: / Line 307: @@
   $ echo out > /sys/class/gpio/gpio211/direction
   $ echo 1 > /sys/class/gpio/gpio211/value
 [[Category:How_to_-_general]]