Re: [PATCH v6 1/4] arm64: dts: qcom: add data-lanes and link-freuencies into dp_out endpoint

[Dmitry Baryshkov]

On 01/12/2022 19:32, Kuogee Hsieh wrote:
> On 11/30/2022 4:21 PM, Dmitry Baryshkov wrote:
> > On 01/12/2022 02:07, Dmitry Baryshkov wrote:
> > > On 01/12/2022 01:51, Kuogee Hsieh wrote:
> > > > Move data-lanes property from mdss_dp node to dp_out endpoint. Also
> > > > add link-frequencies property into dp_out endpoint as well. The last
> > > > frequency specified at link-frequencies will be the max link rate
> > > > supported by DP.
> > > >
> > > > Changes in v5:
> > > > -- revert changes at sc7180.dtsi and sc7280.dtsi
> > > > -- add &dp_out to sc7180-trogdor.dtsi and sc7280-herobrine.dtsi
> > > >
> > > > Changes in v6:
> > > > -- add data-lanes and link-frequencies to yaml
> > > >
> > > > Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> > > > ---
> > > >   .../devicetree/bindings/display/msm/dp-controller.yaml  | 17 
> > > > +++++++++++++++++
> > >
> > > Separate patch. Also you didn't check the get_maintainers output, so 
> > > required parties were not included into the distribution.
> > >
> > > Also as you'd check the get_maintainers output, please fix other 
> > > email addresses too.
> > >
> > > > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi            |  6 +++++-
> > > >   arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi          |  6 +++++-
> > > >   3 files changed, 27 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git 
> > > > a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml 
> > > > b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > > > index 94bc6e1..af70343 100644
> > > > --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > > > +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > > > @@ -90,6 +90,20 @@ properties:
> > > >           $ref: /schemas/graph.yaml#/properties/port
> > > >           description: Output endpoint of the controller
> > > > +        properties:
> > > > +          endpoint:
> > > > +            $ref: /schemas/media/video-interfaces.yaml#
> > > > +
> > > > +          properties:
> > > > +            link-frequencies: true
> > > > +            data-lanes: true
> > >
> > > No. Use $ref for both of them.
> > >
> > > > +
> > > > +          required:
> > > > +            - link-frequencies
> > > > +            - data-lanes
> > >
> > > No, they are not required.
> > >
> > > > +
> > > > +          additionalProperties: false
> > > > +
> > >
> > > deprecation of old data-lanes property?
> > >
> > > >   required:
> > > >     - compatible
> > > >     - reg
> > > > @@ -158,6 +172,9 @@ examples:
> > > >                   reg = <1>;
> > > >                   endpoint {
> > > >                       remote-endpoint = <&typec>;
> > > > +                    data-lanes = <1 2>;
> > > > +                    link-frequencies = /bits/ 64 <160000000 270000000
> >
> > s/1600/1620
> >
> > > > + 540000000 810000000>;
> > >
> > > I guess the number of zeroes is wrong here. This is 160 MHz ... 810 
> > > Mhz, rather than 1.6 GHz ... 8.1 GHz
> >
> > Ok, I was wrong here. The old code definitely defaults to 570 
> > mega-something. Now I'd really like to read your description for the 
> > link-frequencies property, because the 
> > phy_configure_opts_dp::link_rate is clearly specified in Mb/s and it 
> > takes a fixed set of values from 1.62 Gb/s up to 8.1 Gb/s.
> >
> > I think the drm_dp_bw_code_to_link_rate() function is incorrect by 
> > itself, as it multiplies with 27000 (27 Mbps) rather than 270000 (0.27 
> > Gbps) as required by the standard. So first, we should fix the 
> > function, then all the rates would become logical.
>
> no, drm_dp_bw_code_to_link_rate() is correct and should not be changes 
> since it impact to other dp drivers too.
>
> 0.27Gbps/lane is specified at DP spec.
>
> DP use 8b/10b coding rule (10 bits symbol contains 8 bits data).

At least it should get documentation that it returns Kylo-bytes per second.

But, getting back to link-frequencies. The documentation clearly says 
that it should be allowed data bus _frequencies_. And frequencies are 
measured in Hz, not in bits/sec or bytes/sec.


> > > >                   };
> > > >               };
> > > >           };
> > > > diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi 
> > > > b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > > > index 754d2d6..39f0844 100644
> > > > --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > > > +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> > > > @@ -812,7 +812,11 @@ hp_i2c: &i2c9 {
> > > >       status = "okay";
> > > >       pinctrl-names = "default";
> > > >       pinctrl-0 = <&dp_hot_plug_det>;
> > > > -    data-lanes = <0 1>;
> > > > +};
> > > > +
> > > > +&dp_out {
> > > > +    data-lanes = <0  1>;
> > > > +    link-frequencies = /bits/ 64 <160000000 270000000 540000000>;
> > >
> > > Same comment here.
> > >
> > > >   };
> > > >   &pm6150_adc {
> > > > diff --git a/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi 
> > > > b/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> > > > index 93e39fc..b7c343d 100644
> > > > --- a/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> > > > +++ b/arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi
> > > > @@ -440,7 +440,11 @@ ap_i2c_tpm: &i2c14 {
> > > >       status = "okay";
> > > >       pinctrl-names = "default";
> > > >       pinctrl-0 = <&dp_hot_plug_det>;
> > > > -    data-lanes = <0 1>;
> > > > +};
> > > > +
> > > > +&dp_out {
> > > > +    data-lanes = <0  1>;
> > > > +    link-frequencies = /bits/ 64 <160000000 270000000 540000000 
> > > > 810000000>;
> > >
> > > And here.
> > >
> > > >   };
> > > >   &mdss_mdp {

--
With best wishes
Dmitry