Panda How to kernel 2 6 39rel

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Introduction

The 2.6.39 kernel has been released, There were many Pandaboard related changes during the release candidate phase, including HDMI, DVI and wl21xx support.


Review of significant release candidates

-rc1

* hdmi & dvi are broken due to some dss clocking issues, see: https://patchwork.kernel.org/patch/674062/ for details, a fix for dvi is available, see below.
* abe sound is not supported.
* Dave Anders patch to not configure the unused power regulators of VUSIM and VAUX1 is included.
* wl12xx support is working to the extent that one can associate with an access point, get an IP address and ping out to the internet.

-rc3

* Rebooting is broken (there was a post suggesting that it was broken in -rc2 as well) follow
this thread for more info: http://www.spinics.net/lists/linux-omap/msg49746.html.
** a simple fix is to turn off OMAP2 support, which is done in the .config below for -rc3.
* What at first looked like interesting changes to /arch/arm/mach-omap2/ /drivers/net/wireless/wl12xx/ /drivers/video/omap2/dss/ 
seemed to really be typo fixes in comments, Hopefully, some real fixes will be in -rc3.
* New in -rc3 is that the usb ethernet adapter appears as eth0 rather than usb0.

-rc6

* lots of (real) changes for omap, see http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.39-rc6 for details.
* Rebooting is still broken, so beware of using omap2plus_defconfig without changes. (see -rc3 above)
* patching is still neccessary to get dvi working
* wlan and ethernet both seem to work as in -rc3, -rc4 and -rc5
* i2c chararacter device driver is still broken, the patch below still applies cleanly and resolves the issue.

-rc7

* No specific PandaBoard changes, but there was work done on /drivers/usb/host/ehci-omap.c
* A new version of wlan firmware (see below) became available which might have working bluetooth.
unfortunately, there is no BT support in the board file /arch/arm/mach-omap2/board-omap4panda.c
* looks like some PandaBoard & OMAP4 specific changes queued up for the next .39-rcx (or maybe .40-rc1)


Wlan

The proper firmware for wl12xx support is available from: git://git.kernel.org/pub/scm/linux/kernel/git/dwmw2/linux-firmware.git, just clone that repository and copy the ti-connectivity directory to /lib/firmware/.

# pwd
/lib/firmware/ti-connectivity
# ls -la
total 1385
drwxr-xr-x    2 root     root          1024 May  9  2011 .
drwxr-xr-x    3 root     root          1024 Dec 31 17:36 ..
-rw-r--r--    1 root     root         48909 May  9  2011 TIInit_7.2.31.bts
-rw-r--r--    1 root     root        273252 May  9  2011 wl1271-fw-2.bin
-rw-r--r--    1 root     root        272784 May  9  2011 wl1271-fw-ap.bin
-rw-r--r--    1 root     root        271832 May  9  2011 wl1271-fw.bin
-rwxr-xr-x    1 root     root          1113 May  9  2011 wl1271-nvs-example-wl128x.bin
-rw-r--r--    1 root     root           912 May  9  2011 wl1271-nvs.bin
-rw-r--r--    1 root     root        265196 May  9  2011 wl128x-fw-ap.bin
-rwxr-xr-x    1 root     root        272748 May  9  2011 wl128x-fw.bin


Building

Building 2.6.39 is basically the same as How to build 2.6.38 kernel, but of course you need the released sources. The omap2plus_defconfig works, but does not enable anything interesting. config.2.6.39-rc1 enables USB, its' ethernet adapter, and wl12xx support. config.2.6.39-rc1.2 enables USB, it's ethernet adapter, wl12xx support, and dvi support,. However using that config requires that the kernel sources be patched with 0001-omap4-pandaboard-fix-dvi-support.patch The patch also provices panda_dvi_defconfig which just enables dvi. The patche applies cleanly to the released sources.

DVI Patch

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

patch -p1 < 0001-omap4-pandaboard-fix-dvi-support.patch

Then use either of the above configs or

make ARCH=arm omap2plus_defconfig
        or
make ARCH=arm panda_dvi_defconfig

Then compile with

make ARCH=arm CROSS_COMPILE=Path_to_your/arm-2009q3/bin/arm-none-linux-gnueabi- uImage
     or
make ARCH=arm CROSS_COMPILE=Path_to_your/arm-2010q1/bin/arm-none-linux-gnueabi- uImage


i2c character device driver

Ever since 2.6.38, the i2c character device driver support from user space has been broken for OMAP44xx.
* A fix has been submitted for the linux-omap-2.6 branch, but it may be a while till it gets into an -rcx.
See http://git.kernel.org/?p=linux/kernel/git/tmlind/linux-omap-2.6.git;a=commit;h=39fe1a6fafe1e85c183379af9f3ceda7cd24bd65 for the commit.
* A quick fix for this issue is available File:Omap44xx-i2c-fix.patch

I2C Patch

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

patch -p1 < Omap44xx-i2c-fix.patch

Then compile as above.


Testing

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

Fbtest.jpg

Then 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: -- -- -- -- -- -- -- --

Stay tuned for the 2.6.40-rcx series where there should be some new features as well as some more bug squashing.