Re: [linuxtv-media:master 471/499] e4000.c:undefined reference to `v4l2_ctrl_handler_free'

[Mauro Carvalho Chehab <m.chehab@samsung.com>]

Em Sun, 16 Mar 2014 13:10:04 +0100
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> On 03/16/2014 01:26 AM, Mauro Carvalho Chehab wrote:
> > Em Sat, 15 Mar 2014 18:34:16 +0200
> > Antti Palosaari <crope@iki.fi> escreveu:
> > 
> >> Mauro,
> >> I am not sure how this should be resolved. E4000 has already depends to 
> >> VIDEO_V4L2. Should VIDEO_V4L2 selected in config MEDIA_SUBDRV_AUTOSELECT ?
> > 
> > The problem is likely with the Kconfig at the dvb driver. You should
> > remember that select doesn't recursively select the dependencies.
> > 
> > So, you should either make the v4l2 control framework optional at
> > e4000 or to make VB_USB_RTL28XXU to either depend or select
> > V4L2 core.
> > 
> > There's also a third option: add stubs for the v4l2_ctrl_* functions
> > at the *.h file. This way, if V4L2 is not compiled, the functions
> > won't do anything. Perhaps this is the most elegant solution.
> > 
> > Hans,
> > any comments?
> 
> I am hesitant to go in that direction, at least for now. At the moment this is
> a one-off (right?), so keep it in e4000 or rtl28xxu. When we get more of these
> dependencies, then I'd like to get a better understanding where things are heading
> with this.

Well, all tuners may potentially have it, as they have some controls.
This is somewhat like the subdev: those controls are generally not
required for DVB or V4L normal usage, as the tuner drivers have a
preset based on the video standard that will be received, optimizing
the tuner for the modulation of the signal.

However, as, in SDR, the tuner driver doesn't know nothing about the
signal to be received, those controls are needed there.

Btw, on a previous git changeset from Antti, there was patches adding 
v4l2 controls to r820t too. He removed on his last rebase, but I'm
pretty sure that the other tuners used by SDR will need that.

Forcing a DVB-only driver to require the full V4L2 stack, just due to
some controls that will never be used there is not nice.

> It's always easier to make such decisions if you have a few more use-cases.
> 
> Regards,
> 
> 	Hans
> 
> > 
> > Regards,
> > Mauro
> > 
> > 
> >>
> >> regards
> >> Antti
> >>
> >>
> >> On 15.03.2014 14:18, kbuild test robot wrote:
> >>> tree:   git://linuxtv.org/media_tree.git master
> >>> head:   ed97a6fe5308e5982d118a25f0697b791af5ec50
> >>> commit: adaa616ffb697f00db9b4ccb638c5e9e719dbb7f [471/499] [media] e4000: implement controls via v4l2 control framework
> >>> config: i386-randconfig-j4-03151459 (attached as .config)
> >>>
> >>> All error/warnings:
> >>>
> >>> warning: (DVB_USB_RTL28XXU) selects MEDIA_TUNER_E4000 which has unmet direct dependencies ((MEDIA_ANALOG_TV_SUPPORT || MEDIA_DIGITAL_TV_SUPPORT || MEDIA_RADIO_SUPPORT) && MEDIA_SUPPORT && I2C && VIDEO_V4L2)
> >>>     drivers/built-in.o: In function `e4000_remove':
> >>>>> e4000.c:(.text+0x541015): undefined reference to `v4l2_ctrl_handler_free'
> >>>     drivers/built-in.o: In function `e4000_probe':
> >>>>> e4000.c:(.text+0x54219e): undefined reference to `v4l2_ctrl_handler_init_class'
> >>>>> e4000.c:(.text+0x5421ce): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x542204): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x542223): undefined reference to `v4l2_ctrl_auto_cluster'
> >>>>> e4000.c:(.text+0x542253): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x542289): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x5422a8): undefined reference to `v4l2_ctrl_auto_cluster'
> >>>>> e4000.c:(.text+0x5422d8): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x54230e): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x54232d): undefined reference to `v4l2_ctrl_auto_cluster'
> >>>>> e4000.c:(.text+0x54235d): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x542393): undefined reference to `v4l2_ctrl_new_std'
> >>>>> e4000.c:(.text+0x5423b2): undefined reference to `v4l2_ctrl_auto_cluster'
> >>>>> e4000.c:(.text+0x5423d8): undefined reference to `v4l2_ctrl_handler_free'
> >>>
> >>> ---
> >>> 0-DAY kernel build testing backend              Open Source Technology Center
> >>> http://lists.01.org/mailman/listinfo/kbuild                 Intel Corporation
> >>>
> >>
> >>
> > 
> > 
> 


-- 

Regards,
Mauro