On Fri, Aug 03, 2018 at 10:40:02AM +0200, Peter Rosin wrote: > On 2018-08-03 10:11, jacopo mondi wrote: > > Hi Peter! > > > > On Fri, Aug 03, 2018 at 09:23:07AM +0200, Peter Rosin wrote: > >> With bus-type/bus-width properties in the endpoint nodes, the video- > >> interface of the connection can be specified for cases where the > >> heuristic fails to select the correct output mode. This can happen > >> e.g. if not all RGB pins are routed on the PCB; the driver has no > >> way of knowing this, and needs to be told explicitly. > >> > >> This is critical for the devices that have the "conflicting output > >> formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant > >> RGB bits move around depending on the selected output mode. For > >> devices that do not have the "conflicting output formats" issue > >> (SAMA5D2, SAMA5D4), this is completely irrelevant. > >> > >> Acked-by: Boris Brezillon <[email protected]> > >> Reviewed-by: Rob Herring <[email protected]> > >> Signed-off-by: Peter Rosin <[email protected]> > >> --- > >> .../devicetree/bindings/display/atmel/hlcdc-dc.txt | 26 > >> ++++++++++++++++++++++ > >> 1 file changed, 26 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >> b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >> index 82f2acb3d374..9de434a8f523 100644 > >> --- a/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >> +++ b/Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt > >> @@ -15,6 +15,14 @@ Required children nodes: > >> to external devices using the OF graph reprensentation (see > >> ../graph.txt). > >> At least one port node is required. > >> > >> +Optional properties in grandchild nodes: > >> + Any endpoint grandchild node may specify a desired video interface > >> + according to ../../media/video-interfaces.txt, specifically > >> + - bus-type: must be <0>. > > > > Is there any value in specifying this, if it has a fixed value to > > "autodetect"? I understand it's optional, so if nobody else objects, > > feels free to keep it there. > > That's just how media/video-interfaces.txt works. > > bus-type 0 means that other properties describe the bus type. In this > case bus-width is specified, so that means a parallel bus. But bus-width > has no meaning (or may not have) if bus-type is non-zero. But checking > that bus-type for zero in the code seemed like overkill to me since the > driver already knows that it is a parallel bus... >
Yeah, I felt like pointing that out since you're not cheking for its value,
and that property is only used by v4l2-fwnode to handle some
not-that-used-anymore bus as CCP2 is.
> TL;DR I'd like to keep it.
>
Fine with me then.
> >
> >> + - bus-width: recognized values are <12>, <16>, <18> and <24>, and
> >> + override any output mode selection heuristic, forcing "rgb444",
> >> + "rgb565", "rgb666" and "rgb888" respectively.
> >> +
> >> Example:
> >>
> >> hlcdc: hlcdc@f0030000 {
> >> @@ -50,3 +58,21 @@ Example:
> >> #pwm-cells = <3>;
> >> };
> >> };
> >> +
> >
> > Two blank lines here.
> >
> >> +
> >> +Example 2: With a video interface override to force rgb565; as above
> >> +but with these changes/additions:
> >> +
> >> + &hlcdc {
> >> + hlcdc-display-controller {
> >> + pinctrl-names = "default";
> >> + pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb565>;
> >> +
> >> + port@0 {
> >
> > The node has a unit address specified, you're missing a reg = <0>
> > property (no big deal, it's an example, but the other one has it)
> >
> >> + hlcdc_panel_output: endpoint@0 {
> >
> > Missing reg here too.
>
> I'll fix those (I think they appeared for the original example after I
> wrote the patch).
>
Ok, then please consider also describing the port@0 node cell sizes too
since it has a child endpoint node.
Cheers
j
> Cheers,
> Peter
>
> > Minors apart:
> >
> > Reviewed-by: Jacopo Mondi <[email protected]>
> >
> > Thanks
> > j
> >
> >> + bus-type = <0>;
> >> + bus-width = <16>;
> >> + };
> >> + };
> >> + };
> >> + };
> >> --
> >> 2.11.0
> >>
>
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