linux-kernel - Re: [v4 1/5] dt-bindings: mfd: Add aspeed pwm-tach binding

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Message-ID: <A5EA19E5-21D8-4954-9636-9B28AC8D946A@aspeedtech.com>
Date:   Fri, 9 Dec 2022 00:54:13 +0000
From:   Billy Tsai <billy_tsai@...eedtech.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "joel@....id.au" <joel@....id.au>,
        "andrew@...id.au" <andrew@...id.au>,
        "lee@...nel.org" <lee@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "corbet@....net" <corbet@....net>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [v4 1/5] dt-bindings: mfd: Add aspeed pwm-tach binding

On 2022/11/23, 4:27 PM, "Krzysztof Kozlowski" <krzysztof.kozlowski@...aro.org> wrote:

    On 23/11/2022 09:24, Krzysztof Kozlowski wrote:
    > > On 23/11/2022 07:16, Billy Tsai wrote:
    > >> Add device binding for aspeed pwm-tach device which is a multi-function
    > >> device include pwm and tach function.
    > > 
    > > Subject: drop second, redundant "bindings".
    > > Also use proper PATCH prefix.
    > > 
    > >>
    > >> Signed-off-by: Billy Tsai <billy_tsai@...eedtech.com>
    > >> ---
    > >>  .../bindings/mfd/aspeed,ast2600-pwm-tach.yaml | 73 +++++++++++++++++++
    > >>  1 file changed, 73 insertions(+)
    > >>  create mode 100644 Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
    > >>
    > >> diff --git a/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
    > >> new file mode 100644
    > >> index 000000000000..e2a7be2e0a18
    > >> --- /dev/null
    > >> +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
    > >> @@ -0,0 +1,73 @@
    > >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
    > >> +# Copyright (C) 2021 Aspeed, Inc.
    > >> +%YAML 1.2
    > >> +---
    > >> +$id: http://devicetree.org/schemas/mfd/aspeed,ast2600-pwm-tach.yaml#
    > >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
    > >> +
    > >> +title: PWM Tach controller
    > >> +
    > >> +description: |
    > >> +  The PWM Tach controller is represented as a multi-function device which
    > >> +  includes:
    > >> +    PWM
    > >> +    Tach
    > >> +
    > >> +maintainers:
    > >> +  - Billy Tsai <billy_tsai@...eedtech.com>
    > >> +
    > >> +properties:
    > >> +  compatible:
    > >> +    items:
    > >> +      - enum:
    > >> +          - aspeed,ast2600-pwm-tach
    > >> +      - const: syscon
    > >> +      - const: simple-mfd
    > >> +
    > >> +  reg:
    > >> +    maxItems: 1
    > >> +
    > >> +  clocks:
    > >> +    maxItems: 1
    > >> +
    > >> +  resets:
    > >> +    maxItems: 1
    > > 
    > > If this is simple-mfd then it cannot take clocks or resets.  Usually the
    > > recommendation for such case is: This is not simple-mfd, drop it. Drop
    > > also syscon and make a proper device.
    > > 
    > > However I am surprised to see such change, so I have no clue why this
    > > was done.

    > Actually now I see it was like that in previous patch, I just missed it
    > during previous review. Anyway this must be fixed.

I have two module (PWM and TACH) but share with the same base address,
The PWM will use the offset (N*0x10) + 0x0 and 0x04.
The TACH will use the offset (N*0x10) + 0x8 and 0x0c.
The range of the N is 0~15.
Can you give me some advice to fix this problem without using simple-mfd?

Thanks

Best Regards,
Billy Tsai