Re: [PATCH 00/24] device link, bridge supplier <-> drm device

Peter Rosin
2018-04-27T07:37:25Z

On 2018-04-27 09:11, Andrzej Hajda wrote:
> Hi Peter,
>
> On 27.04.2018 00:31, Peter Rosin wrote:
>> Hi!
>>
>> It was noted by Russel King [1] that bridges (not using components)
>> might disappear unexpectedly if the owner of the bridge was unbound.
>> Jyri Sarha had previously noted the same thing with panels [2]. Jyri
>> came up with using device links to resolve the panel issue, which
>> was also my (independent) reaction to the note from Russel.
>>
>> This series builds up to the addition of that link in the last
>> patch, but in my opinion the other 23 patches do have merit on their
>> own.
>>
>> The last patch needs testing, while the others look trivial. That
>> said, I might have missed some subtlety.
>
> of_node is used as an identifier of the bridge in the kernel. If you
> replace it with device pointer there will be potential problem with
> devices having two or more bridges, how do you differentiate bridges if
> the owner is the same? If I remember correctly current bridge code does
> not allow to have multiple bridges in one device, but that should be
> quite easy to fix if necessary. After this change it will become more
> difficult.

I don't see how it will be more difficult?

> Anyway I remember discussion that in DT world bridge should be
> identified rather by of_graph port node, not by parent node as it is
> now. If you want to translate this relation to device owner, you should
> add also port number to have full identification of the bridge, ie pair
> (owner, port_number) would be equivalent of port node.

You even state the trivial solution here, just add the port/endpoint ID
when/if it is needed. So, what is the significant difference?

Cheers,
Peter