[PATCH v2] dt-bindings: drm: rcar-du: Document optional reset properties

[Geert Uytterhoeven]

Hi Rob,

On Thu, Mar 16, 2017 at 9:56 PM, Rob Herring <robh at kernel.org> wrote:
> On Thu, Mar 16, 2017 at 09:13:16AM +0100, Geert Uytterhoeven wrote:
>> On Wed, Mar 15, 2017 at 6:01 PM, Rob Herring <robh at kernel.org> wrote:
>> > On Mon, Mar 06, 2017 at 05:25:56PM +0100, Geert Uytterhoeven wrote:
>> >> Document the optional properties for describing module resets, to
>> >> support resetting display channels and LVDS encoders on R-Car Gen2 and
>> >> Gen3.
>> >>
>> >> Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
>> >> ---
>> >> See "[v2,1/4] dt-bindings: clock: renesas: cpg-mssr: Document reset control
>> >> support" (https://patchwork.kernel.org/patch/9536627/) for the format of
>> >> a reset specifier in the Renesas CPG/MSSR case.
>> >>
>> >> E.g. "resets = <&cpg 310>;"
>> >>
>> >> v2:
>> >>   - s/phandles/phandle/.
>> >> ---
>> >>  Documentation/devicetree/bindings/display/renesas,du.txt | 10 ++++++++++
>> >>  1 file changed, 10 insertions(+)
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/display/renesas,du.txt b/Documentation/devicetree/bindings/display/renesas,du.txt
>> >> index 1a02f099a0ff0a3a..3db418c827193e82 100644
>> >> --- a/Documentation/devicetree/bindings/display/renesas,du.txt
>> >> +++ b/Documentation/devicetree/bindings/display/renesas,du.txt
>> >> @@ -36,6 +36,16 @@ Required Properties:
>> >>        When supplied they must be named "dclkin.x" with "x" being the input
>> >>        clock numerical index.
>> >>
>> >> +Optional properties:
>> >> +  - resets: A list of phandle + reset-specifier pairs, one for each entry in
>> >> +    the reset-names property.
>> >> +  - reset-names: Names of the resets. This property is model-dependent.
>> >> +    - R8A779[0123456] use one reset for a group of one or more successive
>> >> +      channels, and one reset per LVDS encoder (if available). The resets
>> >> +      must be named "du.x" with "x" being the numerical index of the lowest
>> >> +      channel in the group. The LVDS resets must be named "lvds.x" with "x"
>> >> +      being the LVDS encoder numerical index.
>> >
>> > LVDS is not a separate block?
>>
>> Well... from a hardware point of view, the LVDS encoders and DU channels
>> are all separate blocks (they have separate reg blocks, clocks, and resets).
>> But due to the dependencies between the blocks, they're modeled in DT as
>> a single device, with multiple reg, clocks, and resets properties.
>
> Dependencies being DRM requirement of wanting a single device with
> sub-devices or some h/w dependencies? The former shouldn't define your
> binding.

Hardware dependencies. Laurent can tell you more about them (when he'll
be back).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds