The 11/01/2021 15:32, Peter Rosin wrote:
Hi Peter,
>
> On 2021-11-01 13:25, Horatiu Vultur wrote:
> > Some HW requires some time for the signals to settle after the muxing is
> > changed. Allow this time to be specified in device tree.
> >
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@xxxxxxxxxxxxx>
> > ---
> > Documentation/devicetree/bindings/i2c/i2c-mux.yaml | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> > index 24cac36037f5..4628ff6340c1 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> > @@ -29,6 +29,12 @@ properties:
> > '#size-cells':
> > const: 0
> >
> > + settle-time-us:
> > + default: 0
> > + description:
> > + The time required for the signals to settle. Currently only the
> > + i2c-mux-gpmux driver supports this optional binding.
>
> The information about how i2c-mux-gpmux is special is bound to go stale,
> and I don't think we should mention such specific details in the binding.
> What I meant was a generic warnings about optional bindings perhaps not
> being supported by all drivers, along the lines of this from i2c.txt:
>
> "These properties may not be supported by all drivers. However, if a driver
> wants to support one of the below features, it should adapt these bindings."
>
> However, I now notice that this sentence makes no sense. It looks like it
> should be s/adapt/adopt/.
>
> And, in the i2c-mux.yaml case it can simply say "Optional properties"
> instead of "These properites" (which refers to a subset of properties
> immediately below the text) since with a yaml binding it is always
> clear which properties are optional and which are required. Lastly, I
> guess this warning belongs in the description.
>
> > +
> > patternProperties:
> > '^i2c@[0-9a-f]+$':
> > $ref: /schemas/i2c/i2c-controller.yaml
> >
>
> Since this is the first optional property, you now need to specify what
> properties are required, which is everything but settle-time-us. If you
> don't, all properties are required. Which is not what we want...
>
> Something like this should do it, I think:
>
> required:
> - compatible
> - '#address-cells'
> - '#size-cells'
Thanks for a detail explanation but I am still struggling with these
bindings. Were you thinking to have something like this?
---
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
index 24cac36037f5..c9fde1bb0fea 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
@@ -19,6 +19,9 @@ description: |+
populating the i2c child busses. If an 'i2c-mux' subnode is present, only
subnodes of this will be considered as i2c child busses.
+ Optional properties may not be supported by all drivers. However, if a driver
+ wants to support one of the below features, it should adopt these bindings.
+
properties:
$nodename:
pattern: '^(i2c-?)?mux'
@@ -29,6 +32,11 @@ properties:
'#size-cells':
const: 0
+ settle-time-us:
+ default: 0
+ description:
+ The time required for the signals to settle.
+
patternProperties:
'^i2c@[0-9a-f]+$':
$ref: /schemas/i2c/i2c-controller.yaml
@@ -41,6 +49,11 @@ patternProperties:
additionalProperties: true
+required:
+ - compatible
+ - '#address-cells'
+ - '#size-cells'
+
examples:
- |
/*
---
If I have this then my problem is with the required properties because then I
start to get new warnings once I run:
make ARCH=arm CROSS_COMPILE=arm-linux- dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/i2c/i2c-mux.yaml
For example, one of new the warnings is this:
/home/hvultur/linux/arch/arm/boot/dts/am335x-icev2.dt.yaml: mux-mii-hog: 'compatible' is a required property
From schema: /home/hvultur/linux/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
/home/hvultur/linux/arch/arm/boot/dts/am335x-icev2.dt.yaml: mux-mii-hog: '#address-cells' is a required property
From schema: /home/hvultur/linux/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
/home/hvultur/linux/arch/arm/boot/dts/am335x-icev2.dt.yaml: mux-mii-hog: '#size-cells' is a required property
From schema: /home/hvultur/linux/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
If I don't have the required properties then I don't see these new warnings.
Does it mean that actually the properties are optional by default?
>
> Cheers,
> Peter
--
/Horatiu
