Re: Automatic device driver back-porting with media_build

[Mason <slash.tmp@free.fr>]

Hello Mauro,

Haven't heard back from you in a while. Maybe someone else can point
out what I'm doing wrong?

On 17/12/2015 13:55, Mauro Carvalho Chehab wrote:

> Mason wrote:
> 
>> I have a TechnoTrend TT-TVStick CT2-4400v2 USB tuner, as described here:
>> http://linuxtv.org/wiki/index.php/TechnoTrend_TT-TVStick_CT2-4400
>>
>> According to the article, the device is supported since kernel 3.19
>> and indeed, if I use a 4.1 kernel, I can pick CONFIG_DVB_USB_DVBSKY
>> and everything seems to work.
>>
>> Unfortunately (for me), I've been asked to make this driver work on
>> an ancient 3.4 kernel.
>
> The goal is to allow compilation since 2.6.32, but please notice that
> not all drivers will go that far. Basically, when the backport seems too
> complex, we just remove the driver from the list of drivers that are
> compiled for a given legacy version.
> 
> See the file v4l/versions.txt to double-check if the drivers you need
> have such restrictions. I suspect that, in the specific case of
> DVB_USB_DVBSKY, it should compile.

Whatever options I pick for my 3.4 config, CONFIG_DVB_USB_DVBSKY remains
unset in v4l/.config

$ grep -r DVB_USB_DVBSKY media_build/v4l/
media_build/v4l/Kconfig:config DVB_USB_DVBSKY
media_build/v4l/Kconfig.kern: [snip config USB]
media_build/v4l/Kconfig.kern: [snip config I2C]
media_build/v4l/.myconfig:CONFIG_DVB_USB_DVBSKY                        := n
media_build/v4l/Makefile.media:obj-$(CONFIG_DVB_USB_DVBSKY) += dvb-usb-dvbsky.o
media_build/v4l/.config:# CONFIG_DVB_USB_DVBSKY is not set

I suppose some prerequisite is missing?
Does anything obvious come to mind?

I've resorted to interrupting the build and changing v4l/.config to
CONFIG_DVB_USB_DVBSKY=m (and the module is correctly built) but this
feels like an unnecessary hack.

Regards.