linux-kernel - Re: [PATCH v7 1/3] media: cec: expose HDMI connector to CEC dev mapping

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Date:   Wed, 19 Jun 2019 13:26:55 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Dariusz Marcinkiewicz <darekm@...gle.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/3] media: cec: expose HDMI connector to CEC dev
 mapping

On 6/19/19 1:05 PM, Dariusz Marcinkiewicz wrote:
> Hi Hans.
> 
> I would like to come back to this thread.
> 
> On Fri, May 24, 2019 at 11:21 AM Hans Verkuil <hverkuil@...all.nl> wrote:
>>
>> Hi Dariusz,
>>
>> I did some more testing with the Khadas VIM2 and found another problem,
>> something that will, unfortunately, require some redesign.
>>
>> See my comments below...
>>
> ...
>>
>> Another issue here is that when the HDMI driver removes the notifier,
>> then it should also zero the connector info. Remember that both the
>> HDMI and the CEC drivers can be loaded and unloaded independently from
>> one another.
>>
> 
> I took a peek at the changes in
> https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=cec-conn. Do I
> understand it correctly, that the above problem is addressed there by
> unregistering an adapter in cec_notifier_conn_unregister (which will
> result in /dev/cecX node going away)? I wonder to what degree this
> solves the problem of HDMI and CEC drivers being loaded and unloaded
> independently. It seems that in cases where HDMI driver is unloaded
> and then loaded again, counterintuitively, the /dev/cecX might not
> come back again, is this right, or am I missing something? Also, is it
> guaranteed that adapter drivers won't try to access an adapter once it
> gets removed by cec_notifier_conn_unregister?

It's old code, I'm going to do it differently (closer to your version,
actually).

I just pushed my latest code, I'm much happier with it.

I'll try to post a patch series this week.

Regards,

	Hans