Re: [PATCH v15 01/32] v4l: async: Remove re-probing support

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On 09/10/17 16:06, Sakari Ailus wrote:
> Hi Mauro,
> 
> On Mon, Oct 09, 2017 at 08:22:39AM -0300, Mauro Carvalho Chehab wrote:
>> Em Thu,  5 Oct 2017 00:50:20 +0300
>> Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> escreveu:
>>
>>> Remove V4L2 async re-probing support. The re-probing support has been
>>> there to support cases where the sub-devices require resources provided by
>>> the main driver's hardware to function, such as clocks.
>>>
>>> Reprobing has allowed unbinding and again binding the main driver without
>>> explicilty unbinding the sub-device drivers. This is certainly not a
>>> common need, and the responsibility will be the user's going forward.
>>>
>>> An alternative could have been to introduce notifier specific locks.
>>> Considering the complexity of the re-probing and that it isn't really a
>>> solution to a problem but a workaround, remove re-probing instead.
>>
>> If the re-probing isn't using anywhere, that sounds a nice cleanup.
>> Did you check if this won't break any driver (like soc_camera)?
> 
> That was discussed earlier in the review; Laurent asked the same question.
> 
> Re-probing never was a proper solution to any problem; it was just a hack
> to avoid unbinding the sensor if the bridge driver was unbound, no more: it
> can't be generalised to support more complex use cases. Mind you, this is
> on devices that aren't actually removable.
> 
> I've briefly discussed this with Laurent; the proper solution would need to
> be implemented in the clock framework instead. There, the existing clocks
> obtained by drivers could be re-activated when the driver for them comes
> back.
> 
> My proposal is that if there's real a need to address this, then it could
> be solved in the clock framework.

Can you add this information to the commit log?

I think that would be very helpful in the future.

Regards,

	Hans



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