On Fri June 28 2013 13:00:43 Mauro Carvalho Chehab wrote: > Em Fri, 28 Jun 2013 10:24:15 +0200 > Hans Verkuil <hverkuil@xxxxxxxxx> 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. Yes, it does have to depend on it. That's exactly why usbtv is failing: like any other v4l2 driver usbtv needs the videodev.ko module. That is dependent on VIDEO_V4L2. What is happening here is that the dependency of usbtv on VIDEO_DEV allows it to be built as part of the kernel, but VIDEO_V4L2 is built as a module due to its I2C dependency with the result that usbtv can't link to the videodev functions. The way things are today I do not believe any v4l2 driver should depend on VIDEO_DEV, instead they should all depend on VIDEO_V4L2. That would make a lot more sense. Hans > > 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--- > > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
