Re: [Gumstix-users] wifi without udev

[Niek K. <n....@tr...>]

If you switch from udev to mdev, you can make mdev load the firmware by
using:

echo /sbin/mdev > /proc/sys/kernel/hotplug

And loading the libertas_sdio manually.

Greetings Niek

Ps my whole mdev script:

#!/bin/sh

echo "Mkdir /dev/pts"
mkdir /dev/pts

echo "Mounting pts"
mount -t devpts devpts /dev/pts

echo "Echoing hotplug"
echo /sbin/mdev > /proc/sys/kernel/hotplug

echo "mdev -s"
mdev -s


-----Original Message-----
From: Frank Agius [mailto:ft...@ya...] 
Sent: Wednesday, March 23, 2011 4:34 PM
To: gum...@li...
Subject: Re: [Gumstix-users] wifi without udev

On 3/22/2011 10:38 PM, dtran11 wrote:
>
> I think I found a way ( source: http://lwn.net/Articles/242046/ ).
I'll try
> to write a script to load the firmware after I do a modprobe of
> libertas_sdio and remove udev once and for all.
>
>
> Firmware loading
> ================
>
> If the hotplug variable FIRMWARE is set, the kernel is requesting
firmware
> for a device (identified by $DEVPATH).  To provide the firmware to the
> kernel,
> do the following:
>
>    echo 1>  /sys/$DEVPATH/loading
>    cat /path/to/$FIRMWARE>  /sys/$DEVPATH/data
>    echo 0>  /sys/$DEVPATH/loading
>
>
In the filesystem on my overo, there is a script called 
/lib/udev/firmware.sh  that loads the libertas firmware.  It looks very 
much like the instructions above.  However the script needs two env 
variables to be set: DEVPATH and FIRMWARE.  They are set by the kernel 
when the libertas_sdio is loaded.  The module also creates the files in 
/sys that you need to poke with the echo.  So you have to sequence it 
correctly, loading the module, waiting for the creation of the env 
variables and /sys files, and then poking with the echo commands. I 
guess that's why loading libertas_sdio takes to long.  Through a little 
debug I found that the env variables are as follows on my system:

DEVPATH=/devices/platform/mmci-omap-hs.1/mmc_host/mmc1/mmc1:0001/mmc1:00
01:1/firmware/mmc1:0001:1
FIRMWARE=libertas/sd8686_helper.bin

However I could not make it work (something in the sequencing may be 
wrong) so I found an alternative.  You can compile the kernel with the 
firmware files built into the kernel, eliminating the need to do so from

user space.  Here are the steps to build the libertas firmware into the 
kernel:

1) copy the firmware files into the kernel source directory "firmware". 
  The files needed for my version of the libertas driver is 
sd8686_helper.bin and sd8686.bin.
2) In the kernel configuration, go to "Device Drivers --> Generic Driver

Options --> External firmware blobs to build into the kernel".  Add the 
string value "sd8686_helper.bin sd8686.bin" (without the quotes). 
Modify the string value if you're using a version of libertas that 
requires another firmware file (could be something like sd8686_v8.bin or

sd8686_v9.bin)
3) recompile the kernel
4) Run the new kernel.  Run "modprobe libertas_sdio".  The libertas and 
libertas_sdio drivers should start and load firmware automatically, 
bringing up wlan0.

I can now start wifi without udev!!

Note the warning the help for kernel option CONFIG_EXTRA_FIRMWARE:
WARNING: If you include additional firmware files into your  binary 
kernel image which are not available under the terms of the GPL, 
then it may be a violation of the GPL to distribute the resulting

frank
>
> dtran11 wrote:
>>
>> It seems like udev is needed because it loads the libertas firmware.
How
>> do I load the firmware manually without udev? I do not need support
for
>> hotplug since all my devices load at startup and udev takes a while
to
>> load.
>>
>> Thanks.
>>
>>
>> dtran11 wrote:
>>>
>>> Hi, I just got an Overo Air for on-board WIFI. I am noticing that
the
>>> wifi card will not start unless udev is enabled. Is there a way to
have
>>> the wifi work without udev?
>>>
>>> Thanks.
>>>
>>
>>
>



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