Re: [PATCH v2 1/4] dt-binding: pinctrl: spacemit: add documents for K1 SoC

[Yixun Lan <dlan@xxxxxxxxxx>]

Hi Krzysztof: 

On 15:48 Sun 25 Aug     , Krzysztof Kozlowski wrote:
> On 25/08/2024 15:10, Yixun Lan wrote:
> > Add dt-binding for the pinctrl driver of SpacemiT's K1 SoC.
> 
> 
> Please use subject prefixes matching the subsystem. You can get them for
> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
> your patch is touching. For bindings, the preferred subjects are
> explained here:
> https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters
> 
> It's "dt-bindings:"
Ok, will fix in next version

> 
> > 
> > Two vendor specific properties are introduced here, As the pinctrl
> > has dedicated slew rate enable control - bit[7], so we have
> > spacemit,slew-rate-{enable,disable} for this. For the same reason,
> > creating spacemit,strong-pull-up for the strong pull up control.
> 
> Huh, no, use generic properties. More on that below
> 
see my reply below

> 
> 
> > 
> > Signed-off-by: Yixun Lan <dlan@xxxxxxxxxx>
> > ---
> >  .../bindings/pinctrl/spacemit,k1-pinctrl.yaml      | 134 +++++++++++++++++
> >  include/dt-bindings/pinctrl/spacemit,k1-pinctrl.h  | 161 +++++++++++++++++++++
> >  2 files changed, 295 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/pinctrl/spacemit,k1-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/spacemit,k1-pinctrl.yaml
> > new file mode 100644
> > index 0000000000000..8adfc5ebbce37
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pinctrl/spacemit,k1-pinctrl.yaml
> > @@ -0,0 +1,134 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/pinctrl/spacemit,k1-pinctrl.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: SpacemiT K1 SoC Pin Controller
> > +
> > +maintainers:
> > +  - Yixun Lan <dlan@xxxxxxxxxx>
> > +
> > +properties:
> > +  compatible:
> > +    const: spacemit,k1-pinctrl
> > +
> > +  reg:
> > +    items:
> > +      - description: pinctrl io memory base
> > +
> > +patternProperties:
> > +  '-cfg$':
> > +    type: object
> > +    description: |
> 
> Do not need '|' unless you need to preserve formatting.
> 
Ok
> > +      A pinctrl node should contain at least one subnode representing the
> > +      pinctrl groups available on the machine.
> > +
> > +    additionalProperties: false
> 
> Keep it before description.
Ok
> 
> > +
> > +    patternProperties:
> > +      '-pins$':
> > +        type: object
> > +        description: |
> > +          Each subnode will list the pins it needs, and how they should
> > +          be configured, with regard to muxer configuration, bias, input
> > +          enable/disable, input schmitt trigger, slew-rate enable/disable,
> > +          slew-rate, drive strength, power source.
> > +        $ref: /schemas/pinctrl/pincfg-node.yaml
> > +
> > +        allOf:
> > +          - $ref: pincfg-node.yaml#
> > +          - $ref: pinmux-node.yaml#
> 
> You are duplicating refs.
ok, will fix it
> 
> > +
> > +        properties:
> > +          pinmux:
> > +            description: |
> > +              The list of GPIOs and their mux settings that properties in the
> > +              node apply to. This should be set using the K1_PADCONF macro to
> > +              construct the value.
> > +            $ref: /schemas/pinctrl/pinmux-node.yaml#/properties/pinmux
> 
> Hm why you need the ref?
> 
will drop it
> > +
> > +          bias-disable: true
> > +
> > +          bias-pull-up: true
> > +
> > +          bias-pull-down: true
> > +
> > +          drive-strength-microamp:
> > +            description: |
> > +              typical current when output high level, but in mA.
> > +              1.8V output: 11, 21, 32, 42 (mA)
> > +              3.3V output: 7, 10, 13, 16, 19, 23, 26, 29 (mA)
> > +            $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +          input-schmitt:
> > +            description: |
> > +              typical threshold for schmitt trigger.
> > +              0: buffer mode
> > +              1: trigger mode
> > +              2, 3: trigger mode
> > +            $ref: /schemas/types.yaml#/definitions/uint32
> > +            enum: [0, 1, 2, 3]
> > +
> > +          power-source:
> > +            description: external power supplies at 1.8v or 3.3v.
> > +            enum: [ 1800, 3300 ]
> > +
> > +          slew-rate:
> > +            description: |
> > +              slew rate for output buffer
> > +              0, 1: Slow speed
> 
> Hm? Surprising, 0 is slow speed?
> 
from docs, section 3.3.2.2 MFPR Register Description
0, 1 are same, both for slow speed
https://developer.spacemit.com/documentation?token=An1vwTwKaigaXRkYfwmcznTXned

> > +              2: Medium speed
> > +              3: Fast speed
> > +            $ref: /schemas/types.yaml#/definitions/uint32
> > +            enum: [0, 1, 2, 3]
> > +
> > +          spacemit,slew-rate-enable:
> > +            description: enable slew rate.
> 
> The presence of slew-rate enables it, doesn't it?
> 
yes, this should work, I will take this approach, thanks

> > +            type: boolean
> > +
> > +          spacemit,slew-rate-disable:
> > +            description: disable slew rate.
> > +            type: boolean
> 
> Just use slew-rate, 0 disable, some value to match real slew-rate.
> 
sounds good to me, since 0, 1 indicate same meaning, can re-use 0 for
disabling slew rate.

> > +
> > +          spacemit,strong-pull-up:
> > +            description: enable strong pull up.
> 
> Do not duplicate the property name in description. You did not say
> anything useful here. What is "strong"? bias-pull-up takes also an argument.
> 
there is a dedicated strong pull bit[3] for I2C, SD card kinds of pad
I don't know how 'strong' it is if in ohms, will see if can get
more info on this (may expand the description)

I think using 'bias-pull-up' property with argument should also work,
but it occur to me it's more intuitive to introduce a property here, which
reflect the underlying hardware functionality. this is similar to starfive's jh7100
bindings/pinctrl/starfive,jh7100-pinctrl.yaml:154
(refer to exist code doesn't mean always correct, so I need advice here)

I will keep this property unless there is objection, please let me know

> > +            type: boolean
> > +
> > +        required:
> > +          - pinmux
> > +
> > +        additionalProperties: false
> 
> This goes up, before description.
> 
Ok
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/pinctrl/spacemit,k1-pinctrl.h>
> > +
> > +    soc {
> > +        #address-cells = <2>;
> > +        #size-cells = <2>;
> > +
> > +        pinctrl@d401e000 {
> > +            compatible = "spacemit,k1-pinctrl";
> > +            reg = <0x0 0xd401e000 0x0 0x400>;
> > +            #pinctrl-cells = <2>;
> > +            #gpio-range-cells = <3>;
> 
> This wasn't ever tested... :(
> ...
will drop it
> 
> > diff --git a/include/dt-bindings/pinctrl/spacemit,k1-pinctrl.h b/include/dt-bindings/pinctrl/spacemit,k1-pinctrl.h
> > new file mode 100644
> > index 0000000000000..13ef4aa6c53a3
> > --- /dev/null
> > +++ b/include/dt-bindings/pinctrl/spacemit,k1-pinctrl.h
> > @@ -0,0 +1,161 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause */
> > +/*
> > + * Copyright (c) 2022-2024 SpacemiT (Hangzhou) Technology Co. Ltd
> > + * Copyright (c) 2024 Yixun Lan <dlan@xxxxxxxxxx>
> > + *
> > + */
> > +
> > +#ifndef _DT_BINDINGS_PINCTRL_K1_H
> > +#define _DT_BINDINGS_PINCTRL_K1_H
> > +
> > +#define PINMUX(pin, mux) \
> > +	(((pin) & 0xffff) | (((mux) & 0xff) << 16))
> > +
> > +/* pin offset */
> > +#define PINID(x)	((x) + 1)
> > +
> > +#define GPIO_INVAL  0
> > +#define GPIO_00     PINID(0)
> 
> Not really, pin numbers are not bindings. Drop entire header.
> 
Ok, I will move them to dts folder, which should be file
arch/riscv/boot/dts/spacemit/k1-pinctrl.h

> ...
> 
> > +
> > +#define SLEW_RATE_SLOW0		0
> > +#define SLEW_RATE_SLOW1		1
> > +#define SLEW_RATE_MEDIUM	2
> > +#define SLEW_RATE_FAST		3
> 
> Not a binding, either. No usage in the driver.
Ok, will drop it

> 
> > +
> > +#define K1_PADCONF(pin, func) (((pin) << 16) | (func))
> 
> Not a binding.
> 
same, move to dts

> 
> 
> Best regards,
> Krzysztof

-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55