Mauro Carvalho Chehab wrote:
quoted text
> On Tue, 06 May 2008 16:34:27 +0200
> Stefan Richter <stefanr@s5r6.in-berlin.de> wrote:
>> But it is /trivial/ to fix.  If A selects B, you have to copy all of B's
>> dependencies to A or select these dependencies by A.
>>
>> So it's totally simple to do it right.  The only nuisance is that you
>> always have to update B's dependencies and selections whenever A's
>> dependencies are changed.
> 
> This is easy to maintain, if you have just a few selects, but this is not the
> case of V4L drivers. Look some examples:
> 
> IVTV driver:
[...]
quoted text
> You may argue to not use select, but it is really hard to avoid, since each of
> those main drivers (cx88, ivtv, bttv, etc) supports a large number of different
> devices, that needs different chips. Most V4L/DVB devices has an internal I2C
> bus that gives the flexibility for the board manufacturers to add/replace the
> internal components at the i2c bus. So, the Kernel uses abstraction layers that
> allows that the same driver to use different internal components.

Shouldn't layers actually untangle dependencies, i.e. concentrate 
dependencies?  A "high-level driver" does not depend on "low-level 
drivers" and the low-level drivers' dependencies anymore.  It only 
depends on a "core driver" and on foreign subsystem APIs.

And yes, the core driver may very well provide some functionality which 
not all of the high-level drivers need, or not all of the low-level 
drivers are able to support.

(All theoretical since I have no idea of what kinds of modules of 
functionality you have/need and whether it really can be simpler organized.)
-- 
Stefan Richter
-=====-==--- -=-= --==-
http://arcgraph.de/sr/
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