Re: [GIT PULL] Move device tree graph parsing helpers to drivers/of

From: Tomi Valkeinen
Date: Fri Mar 14 2014 - 08:44:59 EST


Hi Philipp, Grant,

On 14/03/14 14:19, Philipp Zabel wrote:

>>> People completely disagree about the direction the phandle links should
>>> point in. I am still of the opinion that the generic binding should describe
>>> just the topology, that the endpoint links in the kernel should represent an
>>> undirected graph and the direction of links should not matter at all for the
>>> generic graph bindings.
>>
>> I would also not mandate a specific direction at the of-graph level and leave
>> it to subsystems (or possibly drivers) to specify the direction.
>
> Thank you. Can everybody live with this?

Yes, I'd like to reserve the possibility for double-linking. If the
endpoint links are used to tell the dataflow direction, then
double-linking could be used for bi-directional dataflows.

But this doesn't help much for the video drivers under work, which I
think we are all most interested in at the moment. We still need to
decide how we link the endpoint for those.

I'd like to go forward with the mainline v4l2 style double-linking, as
that is already in use. It would allow us to proceed _now_, and maybe
even get display support to 3.15. Otherwise this all gets delayed for
who knows how long, and the displays in question cannot be used by the
users.

Deprecating the other link later from the existing video bindings would
be trivial, as there would basically be nothing to do except remove the
other link.

Tomi


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