Hi Phillipp,
On Mon, 22 Feb 2016 17:12:27 +0100, Philipp Zabel wrote:
> Am Montag, den 22.02.2016, 14:14 +0000 schrieb John Keeping:
> > Is there a reason why endpoints in a device tree graph can't be
> > disabled?
>
> You can always remove them using /delete-node/, which also has the
> advantage of reminding you not to leave a single dangling endpoint.
Thanks, I wasn't aware of /delete-node/. It does indeed do what I want.
> > I would like to be able to force the use of a particular CRTC for
> > certain outputs even though the hardware is capable of connecting any
> > CRTC to any output. In this case I need to be able to support a wide
> > range of frequencies for external HDMI monitors so I will configure one
> > of the CRTCs to be able to generate these while the other will be tied
> > into a limited set of clock rates as a result of the overall system
> > clock setup.
> >
> > Currently this can only be achieved by removing the endpoints from the
> > base SoC .dtsi file but it feels like it should be possible to add
> > 'status = "disabled"' to the nodes in the board-specific .dts in order
> > to disable undesirable configurations.
> >
> > I tested the change below and it behaves exactly as I want, but I don't
> > claim to understand all of the users of these functions to know if it
> > will break something else (hence this isn't a formal patch).
>
> I don't know that any driver depends on being able to parse disabled
> endpoints, but given the above I'm not sure that keeping disabled
> endpoints in the device tree is a useful feature.
> Disabling ports makes more sense to me. It should be documented in
> Documentation/devicetree/bindings/graph.txt though.
That isn't relevent for my scenario because this case has a port with
multiple endpoints and we only want one of the endpoints to be
available:
vopb_out: port {
#address-cells = <1>;
#size-cells = <0>;
vopb_out_hdmi: endpoint@0 {
reg = <0>;
remote-endpoint = <&hdmi_in_vopb>;
};
vopb_out_mipi: endpoint@1 {
reg = <1>;
remote-endpoint = <&mipi_in_vopb>;
};
};
But I'm happy that /delete-node/ works and seems to be the right thing
to do.
Thanks,
John
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