On Mon, 29 Oct 2007, Ingo Molnar wrote:
* Randy Dunlap <[email protected]> wrote:
config VIDEO_SAA7146_VV
tristate
depends on VIDEO_DEV = y || VIDEO_DEV = VIDEO_SAA7146_VV
select VIDEOBUF_DMA_SG
select VIDEO_SAA7146
(untested)
Nope, won't work. I tried that last night. VIDEO_DEV_SAA7146_VV
has too many "select"s involved, but select doesn't follow the dependency
chains. IOW, as written in Documentation/kbuild/kconfig-language.txt:
select is evil.... select will by brute force set a symbol
equal to 'y' without visiting the dependencies. So abusing
select you are able to select a symbol FOO even if FOO depends
on BAR that is not set.
so ... what should we do? Remove those ~7 select VIDEO_SAA7146_VV lines
and replace them with depends on VIDEO_SAA7146_VV ?
If select is not following the dependency chains, This would mean that we may
need to rewrite also on other parts of /drivers/media Kconfig files that may
be suffering the same kind of trouble.
There are several places where a similar logic is used, to select modules that
are present only on some configurations.
For example, by default, bttv module selects all possible audio TV decoders
that can be needed by a bttv device (msp34xx, tvaudio, tda7432, ...). Just one
audio decoder is needed for a specific bttv hardware. So, there's also an
option to manually select just the needed drivers.
The actual logic is:
menu "Encoders/decoders and other helper chips"
depends on !VIDEO_HELPER_CHIPS_AUTO
config VIDEO_TVAUDIO
tristate "Simple audio decoder chips"
depends on VIDEO_V4L1 && I2C
...
endmenu
config VIDEO_BT848
tristate "BT848 Video For Linux"
depends on VIDEO_DEV && PCI && I2C && VIDEO_V4L1
select I2C_ALGOBIT
select FW_LOADER
select VIDEO_BTCX
select VIDEOBUF_DMA_SG
select VIDEO_IR
select VIDEO_TUNER
select VIDEO_TVEEPROM
select VIDEO_MSP3400 if VIDEO_HELPER_CHIPS_AUTO
select VIDEO_TVAUDIO if VIDEO_HELPER_CHIPS_AUTO
select VIDEO_TDA7432 if VIDEO_HELPER_CHIPS_AUTO
select VIDEO_TDA9875 if VIDEO_HELPER_CHIPS_AUTO
Also, the same audio decoders can be used by other devices. For example,
msp34xx is used also with pvrusb2 and several em28xx devices.
So, converting this to "depend on" won't be trivial, since there's no direct
dependency of a bridge driver (cx88, bttv, pvrusb2) and an auxiliary i2c
device (msp34xx, tvaudio, ir, ...).
There's something weird, though. The select does the proper thing for tuners.
Why is it failing for SAA7146_VV?
--
Cheers,
Mauro
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