On Wednesday 17 March 2010 20:28:07 Mauro Carvalho Chehab wrote:
> Guennadi Liakhovetski wrote:
>
> > Hi Mauro
> >
> > we just discussed this with Hans on IRC, and if I understood him
> > correctly, he was of the same opinion, that adding such a variable could
> > help.
> >
> > The problem is the following: this automatic selection works in a way,
> > that various bridge drivers select "helper" chip drivers (i2c subdevice
> > drivers" if this autoselection is enabled, e.g.
> >
> > config VIDEO_MXB
> > tristate "Siemens-Nixdorf 'Multimedia eXtension Board'"
> > depends on PCI && VIDEO_V4L1 && I2C
> > select VIDEO_SAA7146_VV
> > select VIDEO_TUNER
> > select VIDEO_SAA711X if VIDEO_HELPER_CHIPS_AUTO
> > select VIDEO_TDA9840 if VIDEO_HELPER_CHIPS_AUTO
> > select VIDEO_TEA6415C if VIDEO_HELPER_CHIPS_AUTO
> > select VIDEO_TEA6420 if VIDEO_HELPER_CHIPS_AUTO
> >
> > With SoC-based set ups this cannot work. The only location where this
> > information is available is platform code under arch/... and selecting
> > these drivers from there would be awkward imho.
>
> Kconfig works fine if the var is on another place. So, you could do things
> like:
>
> config VIDEO_xxx
> select VIDEO_foo if VIDEO_HELPER_CHIPS_AUTO && ARCH_bar
>
> You may even convert it into dependencies like:
>
> config VIDEO_I2C_foo
> depends on ARCH_bar && config VIDEO_xxx
> default y if VIDEO_HELPER_CHIPS_AUTO
I2C drivers are NOT dependent on architectures. They can be used anywhere.
>
> The depends on syntax generally works better than using select. We've
> converted
> some select into depends on a few places like tuner, like, for example:
>
> config MEDIA_TUNER_TDA827X
> tristate "Philips TDA827X silicon tuner"
> depends on VIDEO_MEDIA && I2C
> default m if MEDIA_TUNER_CUSTOMISE
>
> > So, for example, we want
> > to put the ak881x video encoder driver under
> >
> > comment "Video encoders"
> >
> > and those drivers are only visible if VIDEO_HELPER_CHIPS_AUTO is
> > unselected, and if it is selected, which it is by default, there is noone
> > to automatically select ak881x. So, I think, the proposed patch is not a
> > work-around, but a reasonable solution for this issue.
>
> Even the menu being invisible, any of the above logic would work, if you do
> something like:
>
> config VIDEO_AK881X
> depends on ARCH_MX1 && I2C
> default y if VIDEO_HELPER_CHIPS_AUTO && SOC_CAMERA
>
> or:
>
> config SOC_CAMERA
> select VIDEO_AK881X if VIDEO_HELPER_CHIPS_AUTO && ARCH_MX1
Same problem here: the architecture does not determine whether this i2c driver
is needed. That is determined by the board definition. I guess the right place
to do this is probably in a 'mach' specific Kconfig like for example
arch/arm/mach-davinci/Kconfig.
But to be honest, I think that the SoC + VIDEO_HELPER_CHIPS_AUTO combination
is pretty pointless.
Regards,
Hans
>
> You should just take some care, since there are some combinations that won't
> work.
> For example, if SOC_CAMERA is a module, any ancillary drivers used by it
> should also
> be 'm', otherwise, the driver will break. That's why, when having multiple
> dependencies, the better is to use the "depends on" way.
>
>
> >
> > Thanks
> > Guennadi
> > ---
> > Guennadi Liakhovetski, Ph.D.
> > Freelance Open-Source Software Developer
> > http://www.open-technology.de/
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-media" in
> > the body of a message to [email protected]
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
>
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
