[PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Jacopo Mondi]

Document the 'initial-reverse-channel-mV' vendor property in the
bindings document of the max9286 driver.

The newly introduced property allows to specifying the initial
configuration of the GMSL reverse control channel to accommodate
remote serializers pre-programmed with the high threshold power
supply noise immunity enabled.

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
index 9ea827092fdd..f61234d204fa 100644
--- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
+++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
@@ -51,6 +51,26 @@ properties:
   '#gpio-cells':
     const: 2

+  maxim,initial-reverse-channel-mV:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    minimum: 30
+    maximum: 200
+    default: 170
+    description: |
+      Initial amplitude of the reverse control channel, in millivolts.
+
+      The initial amplitude shall be adjusted to a value compatible with the
+      configuration of the connected remote serializer.
+
+      Some camera modules (for example RDACM20) include an on-board MCU that
+      pre-programs the embedded serializer with power supply noise immunity
+      (high-threshold) enabled. A typical value of the deserializer's reverse
+      channel amplitude to communicate with pre-programmed serializers is 170mV.
+
+      A typical value for the reverse channel amplitude to communicate with
+      a remote serializer whose high-threshold noise immunity is not enabled
+      is 100mV.
+
   ports:
     type: object
     description: |
@@ -221,6 +241,7 @@ required:
   - ports
   - i2c-mux
   - gpio-controller
+  - maxim,initial-reverse-channel-mV

 additionalProperties: false

@@ -243,6 +264,8 @@ examples:
         gpio-controller;
         #gpio-cells = <2>;

+        maxim,initial-reverse-channel-mV = <170>;
+
         ports {
           #address-cells = <1>;
           #size-cells = <0>;
--
2.29.1

Re: [PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Rob Herring]

On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> Document the 'initial-reverse-channel-mV' vendor property in the
> bindings document of the max9286 driver.
> 
> The newly introduced property allows to specifying the initial
> configuration of the GMSL reverse control channel to accommodate
> remote serializers pre-programmed with the high threshold power
> supply noise immunity enabled.
> 
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> index 9ea827092fdd..f61234d204fa 100644
> --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> @@ -51,6 +51,26 @@ properties:
>    '#gpio-cells':
>      const: 2
> 
> +  maxim,initial-reverse-channel-mV:

Use standard unit suffix.

> +    $ref: '/schemas/types.yaml#/definitions/uint32'
> +    minimum: 30
> +    maximum: 200
> +    default: 170
> +    description: |
> +      Initial amplitude of the reverse control channel, in millivolts.
> +
> +      The initial amplitude shall be adjusted to a value compatible with the
> +      configuration of the connected remote serializer.
> +
> +      Some camera modules (for example RDACM20) include an on-board MCU that
> +      pre-programs the embedded serializer with power supply noise immunity
> +      (high-threshold) enabled. A typical value of the deserializer's reverse
> +      channel amplitude to communicate with pre-programmed serializers is 170mV.
> +
> +      A typical value for the reverse channel amplitude to communicate with
> +      a remote serializer whose high-threshold noise immunity is not enabled
> +      is 100mV.
> +
>    ports:
>      type: object
>      description: |
> @@ -221,6 +241,7 @@ required:
>    - ports
>    - i2c-mux
>    - gpio-controller
> +  - maxim,initial-reverse-channel-mV
> 
>  additionalProperties: false
> 
> @@ -243,6 +264,8 @@ examples:
>          gpio-controller;
>          #gpio-cells = <2>;
> 
> +        maxim,initial-reverse-channel-mV = <170>;
> +
>          ports {
>            #address-cells = <1>;
>            #size-cells = <0>;
> --
> 2.29.1
> 

Re: [PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Jacopo Mondi]

Hello,

On Mon, Nov 30, 2020 at 03:00:48PM -0700, Rob Herring wrote:
> On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> > Document the 'initial-reverse-channel-mV' vendor property in the
> > bindings document of the max9286 driver.
> >
> > The newly introduced property allows to specifying the initial
> > configuration of the GMSL reverse control channel to accommodate
> > remote serializers pre-programmed with the high threshold power
> > supply noise immunity enabled.
> >
> > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> >  .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > index 9ea827092fdd..f61234d204fa 100644
> > --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > @@ -51,6 +51,26 @@ properties:
> >    '#gpio-cells':
> >      const: 2
> >
> > +  maxim,initial-reverse-channel-mV:
>
> Use standard unit suffix.
>

Which one ? :)
I see in v5.10 one 'mV', three 'mv', one 'millivolts', several
'microvolts'.

I'll go with the majority and make this
'maxim,initial-reverse-channel-mv'

Thanks
   j

> > +    $ref: '/schemas/types.yaml#/definitions/uint32'
> > +    minimum: 30
> > +    maximum: 200
> > +    default: 170
> > +    description: |
> > +      Initial amplitude of the reverse control channel, in millivolts.
> > +
> > +      The initial amplitude shall be adjusted to a value compatible with the
> > +      configuration of the connected remote serializer.
> > +
> > +      Some camera modules (for example RDACM20) include an on-board MCU that
> > +      pre-programs the embedded serializer with power supply noise immunity
> > +      (high-threshold) enabled. A typical value of the deserializer's reverse
> > +      channel amplitude to communicate with pre-programmed serializers is 170mV.
> > +
> > +      A typical value for the reverse channel amplitude to communicate with
> > +      a remote serializer whose high-threshold noise immunity is not enabled
> > +      is 100mV.
> > +
> >    ports:
> >      type: object
> >      description: |
> > @@ -221,6 +241,7 @@ required:
> >    - ports
> >    - i2c-mux
> >    - gpio-controller
> > +  - maxim,initial-reverse-channel-mV
> >
> >  additionalProperties: false
> >
> > @@ -243,6 +264,8 @@ examples:
> >          gpio-controller;
> >          #gpio-cells = <2>;
> >
> > +        maxim,initial-reverse-channel-mV = <170>;
> > +
> >          ports {
> >            #address-cells = <1>;
> >            #size-cells = <0>;
> > --
> > 2.29.1
> >

Re: [PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Geert Uytterhoeven]

Hi Jacopo,

On Tue, Dec 15, 2020 at 12:14 PM Jacopo Mondi <jacopo@jmondi.org> wrote:
> On Mon, Nov 30, 2020 at 03:00:48PM -0700, Rob Herring wrote:
> > On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> > > Document the 'initial-reverse-channel-mV' vendor property in the
> > > bindings document of the max9286 driver.
> > >
> > > The newly introduced property allows to specifying the initial
> > > configuration of the GMSL reverse control channel to accommodate
> > > remote serializers pre-programmed with the high threshold power
> > > supply noise immunity enabled.
> > >
> > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > > ---
> > >  .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
> > >  1 file changed, 23 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > index 9ea827092fdd..f61234d204fa 100644
> > > --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > @@ -51,6 +51,26 @@ properties:
> > >    '#gpio-cells':
> > >      const: 2
> > >
> > > +  maxim,initial-reverse-channel-mV:
> >
> > Use standard unit suffix.
> >
>
> Which one ? :)

Documentation/devicetree/bindings/property-units.txt

> I see in v5.10 one 'mV', three 'mv', one 'millivolts', several
> 'microvolts'.
>
> I'll go with the majority and make this
> 'maxim,initial-reverse-channel-mv'

Wrong guess ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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

Re: [PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Jacopo Mondi]

Hi Geert,

On Tue, Dec 15, 2020 at 12:44:17PM +0100, Geert Uytterhoeven wrote:
> Hi Jacopo,
>
> On Tue, Dec 15, 2020 at 12:14 PM Jacopo Mondi <jacopo@jmondi.org> wrote:
> > On Mon, Nov 30, 2020 at 03:00:48PM -0700, Rob Herring wrote:
> > > On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> > > > Document the 'initial-reverse-channel-mV' vendor property in the
> > > > bindings document of the max9286 driver.
> > > >
> > > > The newly introduced property allows to specifying the initial
> > > > configuration of the GMSL reverse control channel to accommodate
> > > > remote serializers pre-programmed with the high threshold power
> > > > supply noise immunity enabled.
> > > >
> > > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > > > ---
> > > >  .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
> > > >  1 file changed, 23 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > index 9ea827092fdd..f61234d204fa 100644
> > > > --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > @@ -51,6 +51,26 @@ properties:
> > > >    '#gpio-cells':
> > > >      const: 2
> > > >
> > > > +  maxim,initial-reverse-channel-mV:
> > >
> > > Use standard unit suffix.
> > >
> >
> > Which one ? :)
>
> Documentation/devicetree/bindings/property-units.txt
>

Oh, I had no idea we have this.
It's been here since a long time it seems, my bad
        Date:   Mon Feb 8 10:55:55 2016

> > I see in v5.10 one 'mV', three 'mv', one 'millivolts', several
> > 'microvolts'.
> >
> > I'll go with the majority and make this
> > 'maxim,initial-reverse-channel-mv'
>
> Wrong guess ;-)
>

Maybe a stupid question, but the fact only 'microvolts' is listed, is
an implied suggestion to use 'millivolts' for simmetry or to express
the value in micro volts ?

> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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

Re: [PATCH v5 2/8] dt-bindings: media: max9286: Document 'maxim,initial-reverse-channel-mV'

[Rob Herring]

On Tue, Dec 15, 2020 at 6:08 AM Jacopo Mondi <jacopo@jmondi.org> wrote:
>
> Hi Geert,
>
> On Tue, Dec 15, 2020 at 12:44:17PM +0100, Geert Uytterhoeven wrote:
> > Hi Jacopo,
> >
> > On Tue, Dec 15, 2020 at 12:14 PM Jacopo Mondi <jacopo@jmondi.org> wrote:
> > > On Mon, Nov 30, 2020 at 03:00:48PM -0700, Rob Herring wrote:
> > > > On Mon, Nov 16, 2020 at 02:52:59PM +0100, Jacopo Mondi wrote:
> > > > > Document the 'initial-reverse-channel-mV' vendor property in the
> > > > > bindings document of the max9286 driver.
> > > > >
> > > > > The newly introduced property allows to specifying the initial
> > > > > configuration of the GMSL reverse control channel to accommodate
> > > > > remote serializers pre-programmed with the high threshold power
> > > > > supply noise immunity enabled.
> > > > >
> > > > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > > > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > > > > ---
> > > > >  .../bindings/media/i2c/maxim,max9286.yaml     | 23 +++++++++++++++++++
> > > > >  1 file changed, 23 insertions(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > > index 9ea827092fdd..f61234d204fa 100644
> > > > > --- a/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > > +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
> > > > > @@ -51,6 +51,26 @@ properties:
> > > > >    '#gpio-cells':
> > > > >      const: 2
> > > > >
> > > > > +  maxim,initial-reverse-channel-mV:
> > > >
> > > > Use standard unit suffix.
> > > >
> > >
> > > Which one ? :)
> >
> > Documentation/devicetree/bindings/property-units.txt
> >
>
> Oh, I had no idea we have this.
> It's been here since a long time it seems, my bad
>         Date:   Mon Feb 8 10:55:55 2016
>
> > > I see in v5.10 one 'mV', three 'mv', one 'millivolts', several
> > > 'microvolts'.
> > >
> > > I'll go with the majority and make this
> > > 'maxim,initial-reverse-channel-mv'
> >
> > Wrong guess ;-)
> >
>
> Maybe a stupid question, but the fact only 'microvolts' is listed, is
> an implied suggestion to use 'millivolts' for simmetry or to express
> the value in micro volts ?

Use microvolts. Not having every possible unit is on purpose.

Rob