linux-kernel - Re: [PATCH] pinctrl/sunxi: adding input-debounce-ns property

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Message-ID: <20210217110313.ly5ly5u5vyh2s7dh@gilmour>
Date:   Wed, 17 Feb 2021 12:03:13 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Marjan Pascolo <marjan.pascolo@...xom.it>
Cc:     wens@...e.org, Jernej Skrabec <jernej.skrabec@...l.net>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl/sunxi: adding input-debounce-ns property

Hi,

On Wed, Feb 10, 2021 at 05:22:37PM +0100, Marjan Pascolo wrote:
> On Allwinner SoC interrupt debounce can be controlled by two oscillator
> (32KHz and 24MHz) and a prescale divider.
> Oscillator and prescale divider are set through
> device tree property "input-debounce" which have 1uS accuracy.
> For acheive nS precision a new device tree poperty is made
> named "input-debounce-ns".
> "input-debounce-ns" is checked only if "input-debounce"
> property is not defined.
> 
> Suggested-by: Maxime Ripard <maxime@...no.tech>
> Signed-off-by: Marjan Pascolo <marjan.pascolo@...xom.it>
> ---
> ---
>  .../pinctrl/allwinner,sun4i-a10-pinctrl.yaml  |  9 +++++++
>  drivers/pinctrl/sunxi/pinctrl-sunxi.c         | 25 ++++++++++++++++---
>  2 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git
> a/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> b/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> index 5240487dfe50..346776de3a44 100644
> ---
> a/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> +++
> b/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> @@ -93,6 +93,15 @@ properties:
>      minItems: 1
>      maxItems: 5
> 
> +  input-debounce-ns:
> +    description:
> +      Debouncing periods in nanoseconds, one period per interrupt
> +      bank found in the controller.
> +      Only checked if input-debounce is not present
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 1
> +    maxItems: 5
> +

This should be a separate patch, with the DT maintainers in Cc. 

You should enforce that the properties are mutually exclusive through
the schema too

>  patternProperties:
>    # It's pretty scary, but the basic idea is that:
>    #   - One node name can start with either s- or r- for PRCM nodes,
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> index dc8d39ae045b..869b6d5743ba 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> @@ -1335,14 +1335,31 @@ static int sunxi_pinctrl_setup_debounce(struct
> sunxi_pinctrl *pctl,
>      struct clk *hosc, *losc;
>      u8 div, src;
>      int i, ret;
> +    /* Keeping for loop below clean */
> +    const char* debounce_prop_name;
> +    unsigned long debounce_dividend;
> 
>      /* Deal with old DTs that didn't have the oscillators */
>      if (of_clk_get_parent_count(node) != 3)
>          return 0;
> 
> +    /*
> +     * Distinguish between simple input-debounce
> +     * and new input-debounce-ns
> +     */
> +

I'm not sure that comment should stay, the code is obvious enough

>      /* If we don't have any setup, bail out */
> -    if (!of_find_property(node, "input-debounce", NULL))
> -        return 0;
> +    if (!of_find_property(node, "input-debounce", NULL)) {
> +        if(!of_find_property(node, "input-debounce-ns", NULL)) {
> +            return 0;
> +        } else {
> +            debounce_prop_name="input-debounce-ns";
> +            debounce_dividend=NSEC_PER_SEC;
> +        }
> +    } else {
> +        debounce_prop_name="input-debounce";
> +        debounce_dividend=USEC_PER_SEC;
> +    }

This doesn't follow the kernel coding style, make sure to run
scripts/checkpatch.pl on your patches before sending them.

Maxime

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