Messages in this thread | | | From | Grant Likely <> | Subject | Re: [PATCH v4 1/3] [media] of: move graph helpers from drivers/media/v4l2-core to drivers/of | Date | Thu, 20 Mar 2014 22:26:31 +0000 |
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On Mon, 10 Mar 2014 08:34:54 +0200, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > On 08/03/14 14:23, Grant Likely wrote: > > >>> That's fine. In that case the driver would specifically require the > >>> endpoint to be that one node.... although the above looks a little weird > >> > >> The driver can't require that. It's up to the board designer to decide > >> how many endpoints are used. A driver may say that it has a single input > >> port. But the number of endpoints for that port is up to the use case. > > > > Come now, when you're writing a driver you know if it will ever be > > possible to have more than one port. If that is the case then the > > binding should be specifically laid out for that. If there will never be > > multiple ports and the binding is unambiguous, then, and only then, > > should the shortcut be used, and only the shortcut should be accepted. > > I was talking about endpoints, not ports. There's no unclarity about the > number of ports, that comes directly from the hardware for that specific > component. The number of endpoints, however, come from the board > hardware. The driver writer cannot know that.
Okay, I understand now.
g.
> > Just to be clear, I have no problem with having the option in the > > pattern, but the driver needs to be specific about what layout it > > expects. > > If we forget the shortened endpoint format, I think it can be quite > specific. > > A device has either one port, in which case it should require the > 'ports' node to be omitted, or the device has more than one port, in > which case it should require 'ports' node. > > Note that the original v4l2 binding doc says that 'ports' is always > optional.
The original v4l2 behaviour doesn't need to change. In fact it should not change if it will cause real-world breakage.
g.
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