The 11/02/2021 13:37, Rob Herring wrote: Hi Rob, > > On Mon, Nov 01, 2021 at 10:32:01PM +0100, Horatiu Vultur wrote: > > 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 > > compatible should not be required here. > > > + - '#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 > > This is because of the $nodename pattern being pretty lax and matches > on mux-mii-hog by mistake. We have 2 options. Change the nodename > pattern to '^(i2c-?)?mux(@.*)?$' or add 'select: false'. The former > would still match on 'mux' or 'mux@.*' which might still have problems. > For the latter, we just need to make sure all the i2c-mux schemas have a > $ref to this schema. Also, with that change we'd stop checking 'i2c-mux' > nodes that don't yet have a specific schema. That said, I do lean toward > the latter option. >From what I can see there are only two i2c-mux schemas and both of them have a $ref to this schema [1][2] [1] https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml#L33 [2] https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml#L16 > > Rob -- /Horatiu
