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SubjectRe: [PATCH v4 3/3] Documentation: of: Document graph bindings
On 26/02/14 17:47, Philipp Zabel wrote:

> Ok, that looks compact enough. I still don't see the need to change make
> the remote-endpoint property required to achieve this, though. On the
> other hand, I wouldn't object to making it mandatory either.

Sure, having remote-endpoint as required doesn't achieve anything
particular as such. I just feel it's cleaner. If you have an endpoint,
it must point to somewhere. Maybe it makes the code a tiny bit simpler.

If we do already have users for this that do not have the
remote-endpoint, then we're stuck with having it as optional. If we
don't, I'd rather have it as mandatory.

In any case, it's not a very important thing either way.

>> Of course, it's up to the developer how his dts looks like. But to me it
>> makes sense to require the remote-endpoint property, as the endpoint, or
>> even the port, doesn't make much sense if there's nothing to connect to.
>
> Please let's not make it mandatory for a port node to contain an
> endpoint. For any device with multiple ports we can't use the simplified
> form above, and only adding the (correctly numbered) port in all the
> board device trees would be a pain.

That's true. I went with having the ports in the board file, for example
on omap3 the dss has two ports, and N900 board uses the second one:

&dss {
status = "ok";

pinctrl-names = "default";
pinctrl-0 = <&dss_sdi_pins>;

vdds_sdi-supply = <&vaux1>;

ports {
#address-cells = <1>;
#size-cells = <0>;

port@1 {
reg = <1>;

sdi_out: endpoint {
remote-endpoint = <&lcd_in>;
datapairs = <2>;
};
};
};
};

Here I guess I could have:

&dss {
status = "ok";

pinctrl-names = "default";
pinctrl-0 = <&dss_sdi_pins>;

vdds_sdi-supply = <&vaux1>;
};

&dss_sdi_port {
sdi_out: endpoint {
remote-endpoint = <&lcd_in>;
datapairs = <2>;
};
};

But I didn't like that as it splits the pincontrol and regulator supply
from the port/endpoint, which are functionally linked together.

Actually, somewhat aside the subject, I'd like to have the pinctrl and
maybe regulator supply also per endpoint, but I didn't see how that
would be possible with the current framework. If a board would need to
endpoints for the same port, most likely it would also need to different
sets of pinctrls.

Tomi


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