Re: [PATCH] usbtv: fix dependency

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em Fri, 28 Jun 2013 10:24:15 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> This fixes a dependency problem as found by Randy Dunlap:
> 
> https://lkml.org/lkml/2013/6/27/501
> 
> Mauro, is there any reason for any V4L2 driver to depend on VIDEO_DEV instead of
> just VIDEO_V4L2?
> 
> Some drivers depend on VIDEO_DEV, some on VIDEO_V4L2, some on both. It's all
> pretty chaotic.

It should be noticed that, despite its name, this config is actually a
joint dependency of VIDEO_DEV and I2C that will compile drivers as module
if either I2C or VIDEO_DEV is a module:

	config VIDEO_V4L2
		tristate
		depends on (I2C || I2C=n) && VIDEO_DEV
		default (I2C || I2C=n) && VIDEO_DEV

So, a V4L2 device that doesn't have any I2C device doesn't need to depend
on VIDEO_V4L2. That includes, for example, reversed-engineered webcam
drivers where the sensor code is inside the driver and a few capture-only
device drivers.

It should be noticed, however, that, on several places, the need of adding
a "depends on VIDEO_V4L2" is not needed, as, on some places, the syntax
is:

	if VIDEO_V4L2

	config "driver foo"
	...

	endif

Btw, it could make sense to rename it to something clearer, like
VIDEO_DEV_AND_I2C and define it as:

	config VIDEO_DEV_AND_I2C
		tristate
		depends on I2C && VIDEO_DEV
		default y

Or, even better, to just get rid of it and explicitly add I2C on all
places where it is used.


Regards,
Mauro

> 
> Regards,
> 
> 	Hans
> 
> diff --git a/drivers/media/usb/usbtv/Kconfig b/drivers/media/usb/usbtv/Kconfig
> index 8864436..7c5b860 100644
> --- a/drivers/media/usb/usbtv/Kconfig
> +++ b/drivers/media/usb/usbtv/Kconfig
> @@ -1,6 +1,6 @@
>  config VIDEO_USBTV
>          tristate "USBTV007 video capture support"
> -        depends on VIDEO_DEV
> +        depends on VIDEO_V4L2
>          select VIDEOBUF2_VMALLOC
>  
>          ---help---


-- 

Cheers,
Mauro