dt-bindings: pinctrl: pinctrl-single: Define a max count for "pinctrl-single,gpio-range"

"pinctrl-single,gpio-range" allows us to define a dis-contiguous
range of pinctrl registers that can have different mux settings for
GPIO mode of operation. However, the maxItems seem to be set to 1 in
processed schema for some reason. This is incorrect. For example:
arch/arm64/boot/dts/hisilicon/hi6220.dtsi and others have more than
one dis-contiguous range.

Arbitrarily define a max 100 count to override the defaults.

Signed-off-by: Nishanth Menon <nm@ti.com>
---
I am not sure if I should call this RFC or not.. and if this is even the
right solution.. I am on 2024.05 dt-schema for this check.

I noticed this when adding gpio-ranges for am62p platform:
https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544

It is possible that this is a bug in dt-schema, but I have'nt been able
to track it down either.

behavior seen is the following:
pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>;
generates no warning
However,
pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>, <&mcu_pmx_range 32 2 7>;

generates "is too long" warning.


 Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml | 1 +
 1 file changed, 1 insertion(+)


base-commit: 76db4c64526c5e8ba0f56ad3d890dce8f9b00bbc

On Tue, 18 Jun 2024 11:51:02 -0500, Nishanth Menon wrote:
> "pinctrl-single,gpio-range" allows us to define a dis-contiguous
> range of pinctrl registers that can have different mux settings for
> GPIO mode of operation. However, the maxItems seem to be set to 1 in
> processed schema for some reason. This is incorrect. For example:
> arch/arm64/boot/dts/hisilicon/hi6220.dtsi and others have more than
> one dis-contiguous range.
> 
> Arbitrarily define a max 100 count to override the defaults.
> 
> Signed-off-by: Nishanth Menon <nm@ti.com>
> ---
> I am not sure if I should call this RFC or not.. and if this is even the
> right solution.. I am on 2024.05 dt-schema for this check.
> 
> I noticed this when adding gpio-ranges for am62p platform:
> https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544
> 
> It is possible that this is a bug in dt-schema, but I have'nt been able
> to track it down either.
> 
> behavior seen is the following:
> pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>;
> generates no warning
> However,
> pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>, <&mcu_pmx_range 32 2 7>;
> 
> generates "is too long" warning.
> 
> 
>  Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml: properties:pinctrl-single,gpio-range: {'description': 'Optional list of pin base, nr pins & gpio function', '$ref': '/schemas/types.yaml#/definitions/phandle-array', 'maxItems': 100, 'items': [{'items': [{'description': 'phandle of a gpio-range node'}, {'description': 'pin base'}, {'description': 'number of pins'}, {'description': 'gpio function'}]}]} should not be valid under {'required': ['maxItems']}
	hint: "maxItems" is not needed with an "items" list
	from schema $id: http://devicetree.org/meta-schemas/items.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20240618165102.2380159-1-nm@ti.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

On 12:34-20240618, Rob Herring wrote:
> 
> On Tue, 18 Jun 2024 11:51:02 -0500, Nishanth Menon wrote:
> > "pinctrl-single,gpio-range" allows us to define a dis-contiguous
> > range of pinctrl registers that can have different mux settings for
> > GPIO mode of operation. However, the maxItems seem to be set to 1 in
> > processed schema for some reason. This is incorrect. For example:
> > arch/arm64/boot/dts/hisilicon/hi6220.dtsi and others have more than
> > one dis-contiguous range.
> > 
> > Arbitrarily define a max 100 count to override the defaults.
> > 
> > Signed-off-by: Nishanth Menon <nm@ti.com>
> > ---
> > I am not sure if I should call this RFC or not.. and if this is even the
> > right solution.. I am on 2024.05 dt-schema for this check.
> > 
> > I noticed this when adding gpio-ranges for am62p platform:
> > https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544
> > 
> > It is possible that this is a bug in dt-schema, but I have'nt been able
> > to track it down either.
> > 
> > behavior seen is the following:
> > pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>;
> > generates no warning
> > However,
> > pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>, <&mcu_pmx_range 32 2 7>;
> > 
> > generates "is too long" warning.
> > 
> > 
> >  Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> 
> My bot found errors running 'make dt_binding_check' on your patch:
> 
> yamllint warnings/errors:
> 
> dtschema/dtc warnings/errors:
> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml: properties:pinctrl-single,gpio-range: {'description': 'Optional list of pin base, nr pins & gpio function', '$ref': '/schemas/types.yaml#/definitions/phandle-array', 'maxItems': 100, 'items': [{'items': [{'description': 'phandle of a gpio-range node'}, {'description': 'pin base'}, {'description': 'number of pins'}, {'description': 'gpio function'}]}]} should not be valid under {'required': ['maxItems']}
> 	hint: "maxItems" is not needed with an "items" list
> 	from schema $id: http://devicetree.org/meta-schemas/items.yaml#

yes, I had expected the same, but processed schema indicates a maxItems
of 1 for reasons I am unable to make sense of.. will be great to have
some additional eyes:

https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544#file-processed-schema-pinctrl

next-20240617 baseline

On 6/18/24 1:57 PM, Nishanth Menon wrote:
> On 12:34-20240618, Rob Herring wrote:
>>
>> On Tue, 18 Jun 2024 11:51:02 -0500, Nishanth Menon wrote:
>>> "pinctrl-single,gpio-range" allows us to define a dis-contiguous
>>> range of pinctrl registers that can have different mux settings for
>>> GPIO mode of operation. However, the maxItems seem to be set to 1 in
>>> processed schema for some reason. This is incorrect. For example:
>>> arch/arm64/boot/dts/hisilicon/hi6220.dtsi and others have more than
>>> one dis-contiguous range.
>>>
>>> Arbitrarily define a max 100 count to override the defaults.
>>>
>>> Signed-off-by: Nishanth Menon <nm@ti.com>
>>> ---
>>> I am not sure if I should call this RFC or not.. and if this is even the
>>> right solution.. I am on 2024.05 dt-schema for this check.
>>>
>>> I noticed this when adding gpio-ranges for am62p platform:
>>> https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544
>>>
>>> It is possible that this is a bug in dt-schema, but I have'nt been able
>>> to track it down either.
>>>
>>> behavior seen is the following:
>>> pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>;
>>> generates no warning
>>> However,
>>> pinctrl-single,gpio-range = <&mcu_pmx_range 0 21 7>, <&mcu_pmx_range 32 2 7>;
>>>
>>> generates "is too long" warning.
>>>
>>>
>>>   Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>
>> My bot found errors running 'make dt_binding_check' on your patch:
>>
>> yamllint warnings/errors:
>>
>> dtschema/dtc warnings/errors:
>> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/pinctrl/pinctrl-single.yaml: properties:pinctrl-single,gpio-range: {'description': 'Optional list of pin base, nr pins & gpio function', '$ref': '/schemas/types.yaml#/definitions/phandle-array', 'maxItems': 100, 'items': [{'items': [{'description': 'phandle of a gpio-range node'}, {'description': 'pin base'}, {'description': 'number of pins'}, {'description': 'gpio function'}]}]} should not be valid under {'required': ['maxItems']}
>> 	hint: "maxItems" is not needed with an "items" list
>> 	from schema $id: http://devicetree.org/meta-schemas/items.yaml#
> 
> yes, I had expected the same, but processed schema indicates a maxItems
> of 1 for reasons I am unable to make sense of.. will be great to have
> some additional eyes:
> 

As the warning says, setting the item count is not needed when the
item list content (and therefore item count) is explicitly defined.
The binding is saying there is a single item of 4 elements.

"pinctrl-single,gpio-range"'s type is a single phandle-array[0]. What
you want is an array of phandle-arrays. The length of each is usually
set by the target of the phandle with its #*-cells property.

This binding is a bit of a mess, the phandle is always a pointer to
a node with the cells length hard-coded to 3. This looks to have been done
to allow the driver to use the function "of_parse_phandle_with_args" which
needs a property name for to find the cell count. But that makes no sense
as the count is always 3, the driver cannot accept any other value. The
driver should have just looped of_get_property() 3 times but wanted to
use the helper. So a silly driver mistake has turned into a binding issue.

We should drop the "pinctrl-single,gpio-range" from the binding and
fix the driver.

Andrew

[0] https://patchwork.kernel.org/project/netdevbpf/patch/20220119015038.2433585-1-robh@kernel.org/

> https://gist.github.com/nmenon/7019cd2f24be47997640df5db60a7544#file-processed-schema-pinctrl
> 
> next-20240617 baseline

On 11:19-20240619, Andrew Davis wrote:
[...]

> 
> This binding is a bit of a mess, the phandle is always a pointer to
> a node with the cells length hard-coded to 3. This looks to have been done
> to allow the driver to use the function "of_parse_phandle_with_args" which
> needs a property name for to find the cell count. But that makes no sense
> as the count is always 3, the driver cannot accept any other value. The
> driver should have just looped of_get_property() 3 times but wanted to
> use the helper. So a silly driver mistake has turned into a binding issue.
> 
> We should drop the "pinctrl-single,gpio-range" from the binding and
> fix the driver.

Linus W: pinctrl-single,gpio-range -> any thoughts here? I think it is a
valid (if a bit too flexible design looking at the existing users who
just use a single mux value mapping for all modes)

On 6/21/24 8:36 AM, Nishanth Menon wrote:
> On 11:19-20240619, Andrew Davis wrote:
> [...]
> 
>>
>> This binding is a bit of a mess, the phandle is always a pointer to
>> a node with the cells length hard-coded to 3. This looks to have been done
>> to allow the driver to use the function "of_parse_phandle_with_args" which
>> needs a property name for to find the cell count. But that makes no sense
>> as the count is always 3, the driver cannot accept any other value. The
>> driver should have just looped of_get_property() 3 times but wanted to
>> use the helper. So a silly driver mistake has turned into a binding issue.
>>
>> We should drop the "pinctrl-single,gpio-range" from the binding and
>> fix the driver.

My bad, I meant to say drop "#pinctrl-single,gpio-range-cells" and drop
the phandle from "pinctrl-single,gpio-range".

The #-cells is meant for a producer to define args for a consumer phandle.
This is so common in DT there is a helper function for it. The problem
is the author of the driver here wanted to use that helper, even though it
would be backwards in this case (pinmux is the consumer).

So we have a node inside the pinmux node that exists only to expose a fixed
number (3) of cells so that a different node inside the same pinmux node
could point to itself to make a helper function happy (that didn't need to
be used in the first place)..

Andrew

> 
> Linus W: pinctrl-single,gpio-range -> any thoughts here? I think it is a
> valid (if a bit too flexible design looking at the existing users who
> just use a single mux value mapping for all modes)
>