[PATCH 07/14] media: soc-camera: support deferred probing of clients

[Barry Song]

2013/4/10 Mark Brown <broonie at opensource.wolfsonmicro.com>:
> On Wed, Apr 10, 2013 at 09:53:20PM +0800, Barry Song wrote:
>> 2013/4/10 Guennadi Liakhovetski <g.liakhovetski at gmx.de>:
>
>> >> what about another possible way:
>> >> we let all host and i2c client driver probed in any order,
>
>> > This cannot work, because some I2C devices, e.g. sensors, need a clock
>> > signal from the camera interface to probe. Before the bridge driver has
>> > completed its probing and registered a suitable clock source with the
>> > v4l2-clk framework, sensors cannot be probed. And no, we don't want to
>> > fake successful probing without actually being able to talk to the
>> > hardware.
>
>> i'd say same dependency also exists on ASoC.  a "fake" successful
>> probing doesn't mean it should really begin to work if there is no
>> external trigger source.  ASoC has successfully done that by a machine
>> driver to connect all DAI.
>> a way is we put all things ready in their places, finally we connect
>> them together and launch the whole hardware flow.
>
> In the ASoC case the idea is that drivers should probe as far as they
> can with just the chip and then register with the core.  The machine
> driver defers probing until all components have probed and then runs
> through second stage initialisaton which pulls everything together.

yes. thanks for clarification, Mark. that is really what i want in
soc-camera too.
put all things in their places, and the final connector wait for
everyone and put them in the initialized status.

-barry