videodev: Unknown symbol i2c_unregister_device (in kernels older than 2.6.26)

[Matt Doran <matt.doran@papercut.com>]

Hi there,

I tried using the latest v4l code on an Mythtv box running 2.6.20, but 
the v4l videodev module fails to load with the following warnings:

    videodev: Unknown symbol i2c_unregister_device
    v4l2_common: Unknown symbol v4l2_device_register_subdev


It seems the "i2c_unregister_device" function was added in 2.6.26.   
References to this function in v4l2-common.c are enclosed in an ifdef like:

    #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 26)


However in "v4l2_device_unregister()" in v4l2-device.c, there is a 
reference to "i2c_unregister_device" without any ifdefs.   I am running 
a pretty old kernel, but I'd guess anyone running 2.6.25 or earlier will 
have this problem.   It seems this code was added by Mauro 3 weeks ago 
in this rev:

    http://linuxtv.org/hg/v4l-dvb/rev/87afa7a4ccdf




I also had some other compile problems, but don't have all the details 
(sorry!).  I had to disable the following drivers to get it to compile:

    * CONFIG_VIDEO_PVRUSB2
    * CONFIG_VIDEO_THS7303
    * CONFIG_VIDEO_ADV7343
    * CONFIG_DVB_SIANO_SMS1XXX


Regards,
Matt