On Thu, Jul 03, 2014 at 06:17:24PM -0400, Rob Clark wrote:
> On Thu, Jul 3, 2014 at 12:49 PM, Russell King
> <rmk+kernel@xxxxxxxxxxxxxxxx> wrote:
> > Add a helper to allow encoders to find their possible CRTCs from the
> > OF graph without having to re-implement this functionality. We add a
> > device_node to drm_crtc which corresponds with the port node in the
> > DT description of the CRTC device.
> >
> > We can then scan the DRM device list for CRTCs to find their index,
> > matching the appropriate CRTC using the port device_node, thus building
> > up the possible CRTC mask.
> >
> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> > ---
> > This helper will be shared between imx-drm and Armada DRM, and should
> > be useful for other OF-based drivers. At the moment, this is being
> > sent for comments and acks; I need to build upon this patch in order
> > to convert Armada DRM to DT.
>
> ok, possibly a dumb question, but in my defense I don't claim to be a
> DT expert ;-)
>
> Do you have somewhere handy a example dts which this would be parsing?
> I think that would help me understand this patch a bit better.
The patch is merely moving something that's already being used by
imx-drm into a more convenient location.
The documentation for the "binding" (it isn't really parsing a binding,
merely traversing the graph itself) is:
Documentation/devicetree/bindings/graph.txt
which is shared from the v4l2 code.
To give an example, this is an extract from the imx6qdl dtsi file. I've
cut out a load of stuff which isn't that relevant to the overall
structure. The full stuff is arch/arm/boots/dts/imx6qdl.dtsi.
IPU contains two display interfaces (DIs, aka CRTCs). Each display
interface is connected to a set of muxes, one mux per display bridge
(encoder/connector) which can select between DI0 or DI1. Some chips
have two IPUs, hence four DIs, making it possible to drive the four
display bridges entirely independently.
ipu1: ipu@02400000 {
ipu1_di0: port@2 {
ipu1_di0_hdmi: endpoint@1 {
remote-endpoint = <&hdmi_mux_0>;
};
...
ipu1_di0_lvds1: endpoint@4 {
remote-endpoint = <&lvds1_mux_0>;
};
};
ipu1_di1: port@3 {
ipu1_di0_disp1: endpoint@0 {
};
ipu1_di1_hdmi: endpoint@1 {
remote-endpoint = <&hdmi_mux_1>;
};
...
ipu1_di1_lvds1: endpoint@4 {
remote-endpoint = <&lvds1_mux_1>;
};
};
};
HDMI transmitter component:
hdmi: hdmi@0120000 {
port@0 {
reg = <0>;
hdmi_mux_0: endpoint {
remote-endpoint = <&ipu1_di0_hdmi>;
};
};
port@1 {
reg = <1>;
hdmi_mux_1: endpoint {
remote-endpoint = <&ipu1_di1_hdmi>;
};
};
};
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
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