Panda How to kernel 3 3 rcx

Introduction

The merge window for 3.3 is over and we are currently at v3.3-rc4. Lots of work on the OMAP platforms and on Pandaboard as well as the wl12xx wlan driver . Let's see what the various release candidates have provided.

You can download a tarball of the mainline kernel at http://kernel.org/

or you can clone a copy of mainline kernel with:

git clone http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux
git checkout v3.3-rcx

where x is the release candidate version.

Important Note There has been a lot of work done on the HDMI interface and its related driver omapdrm. Between kernel 3.1 and 3.2-rc1 enough changed so that the Testing section on the HDMI interface is no longer correct. The hdmi init functions are no longer in arch/arm/mach_omap2/board-omap4panda.c. When this situation stabilises, the HDMI testing section below will be updated.

rc1

The following seems to be only true for the PandaBoard ES. Tests with a PandaBoard EA3 confirm that the patch is still needed

The WLAN no longer requires a patch! The WL12xx driver needs current firmware. When the driver isn't happy, the error messages are somewhat less than useful, however the drivers/firmware are being constantly improved and it would not be a good idea to have the driver support anything but the latest firmware. Still a work in progress.

rc2

No PandaBoard changes, and with no patches required this is an easy release to build.

rc3

Skipped due to the HDMI changes which cropped up in 3.2-rc1 Lots of changes working towards getting HDMI functional

rc4

resolve nebulous 'Error setting wl12xx data' fix to PandaBoard. "This should be fixed properly for the next merge window so we don't issue error messages merely because a driver is not configured."

Devicetree-enabled kernels crash during boot due to the UART driver (http://www.spinics.net/lists/linux-omap/msg64921.html). A patch has been proposed and should be merged before release.

rc7

The WL12xx driver still needs the same patch as used for 3.1 and 3.2. when the driver isn't happy, the error messages are somewhat less than useful, however the drivers/firmware are being constantly improved and it would not be a good idea to have the driver support anything but the latest firmware. The race issue that required building as a module has returned and with the modules built in, operation is not consistant.

PandaBoard ES

There is now a PandaBoard ES http://pandaboard.org/content/pandaboard-es which includes an OMAP 4460 at up to 1.2GHz. Several important differences make it important (at the present time) that the MLO/u-boot be specifically crafted for the 4460. The thermal management is not in the mainline 4430 code as yet and therefore the max clock frequency when running the OMAP4460 on the PandaBoard ES with the mainline kernel is 920MHz(same as the OMAP4430).

wlan12xx patch

This patch is still necessary to resolve the issue noted in 3.0, 3.1 and 3.2, the code was moved to twl_common.c.

0001a-omap4-pandaboard-wlan-fix.patch

Apply it like so: (from inside the kernel sources directory)

patch -p1 < 0001a-omap4-pandaboard-wlan-fix.patch

The latest wlan firmware is available from git: git://git.kernel.org/pub/scm/linux/kernel/git/dwmw2/linux-firmware.git just copy the contents of the ti-connectivity folder to /lib/firmware/ti-connectivity.

The patch is no longer necessary for the PandaBoard ES but does not seem to hurt if applied. In addition, the race issue that required building as a module has returned as of -rc2. As part of the code cleanup, the wl12xx and wl12xx_sdio drivers no longer depend on each other. This creates an issue with systems that do not use udev or mdev (with as somewhat fiddly & slow script) to load MODALIAS drivers. The quick solution is to modprobe both, the order no longer matters. Just modprobing wl12xx_sdio will no longer automatically load wl12xx. It is suggested that these 2 drivers be built as modules.

I2C Patch

i2c character device driver patch that has been necessary is no longer required, and the issues from kernel 3.2 have been resolved.

Building

Building 3.3-rc1 or -rc2 is fairly straight forward.

Grab the 3.3-rc1 or 3.3-rc2 sources and use config.3.3-rc1.1 or config.3.3-rc2.1 as the .config

The 3.3-rc1 .config enables Sound builtin and wl12xx as modules and the 3.3-rc2 enables Sound and the wl12xx drivers builtin, so the resulting kernel will be a bit bigger than previously. The builtin sound does not presently work, but the enabled configuration allows USB sound devices, which function properly.

Then compile like so:

make ARCH=arm CROSS_COMPILE=Path_to_your/arm-2010q1/bin/arm-none-linux-gnueabi- uImage

Testing

fbtest on DVI Port

After booting run fbtest to see a nice test pattern from the dvi port.

Switching primary display to the HDMI port --> Currently not functional <--

Make sure that a monitor is plugged into the HDMI port before doing the following:

# Enable HDMI
echo "1" > /sys/devices/platform/omapdss/display1/enabled

# Disable overlay0 (an overlay must be disabled before changing its properties)
echo "0" > /sys/devices/platform/omapdss/overlay0/enabled

# Set the manager of overlay0 to display1 which is HDMI
echo "tv" > /sys/devices/platform/omapdss/overlay0/manager

# Enable overlay0
echo "1" > /sys/devices/platform/omapdss/overlay0/enabled

And content on overlay 0 of primary lcd would be transferred to HDMI. It works similarly for all other overlay's.

Switching primary display to the DVI port

See: http://omappedia.org/wiki/Bootargs_for_enabling_display for lots of useful info on the display subsystem. Be aware that the display, manager and overlay numbers don't match the panda configuration.

Make sure that a monitor is plugged into the DVI port before doing the following:

# Disable HDMI
echo "0" > /sys/devices/platform/omapdss/display1/enabled

# Disable overlay0 (an overlay must be disabled before changing its properties)
echo "0" > /sys/devices/platform/omapdss/overlay0/enabled

# Set the manager of overlay0 to display0 which is DVI
echo "lcd2" > /sys/devices/platform/omapdss/overlay0/manager

# Enable overlay0
echo "1" > /sys/devices/platform/omapdss/overlay0/enabled

The above commands should be run from the serial console and the cable should be in the destination port before running the commands.

fbtest on HDMI Port --> Currently not functional <--

Run fbtest to see a nice test pattern from the HDMI port.

i2cdetect

You can run i2cdetect and the results should look like this:

# i2cdetect -y -r 1
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- UU UU UU UU -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

wlan

Run the following commands after the PandaBoard is booted:

modprobe wl12xx    ** only if you built the wl12xx drivers as modules
modprobe wl12xx_sdio    ** only if you built the wl12xx drivers as module
ifconfig wlan0 up
iwconfig wlan0 essid "Your AccessPoint Name"
udhcpc -i wlan0

If your network is set up to provide DHCP services, the PandaBoard will get all the "right stuff(tm)" and you will be able to access the Internet.

# ping www.google.com
PING www.google.com (74.125.73.99): 56 data bytes
64 bytes from 74.125.73.99: seq=0 ttl=43 time=62.683 ms
64 bytes from 74.125.73.99: seq=1 ttl=43 time=54.077 ms
64 bytes from 74.125.73.99: seq=2 ttl=43 time=51.484 ms
64 bytes from 74.125.73.99: seq=3 ttl=43 time=54.108 ms

USB Performance

Insert a USB memory stick into one of the usb ports

Run dmesg to see what sdx the stick was recognised as, then:

hdparam -tT /dev/sdx

If you did this on a kernel without the patch you will see some improvement, if you run the same command on a desktop Linux system, with the same USB memory stick, the PandaBoard's speed should roughly be the same.