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Message-ID: <B9287FE7-5EF5-40B3-BCB3-08DA11D6CDD7@aspeedtech.com>
Date: Thu, 15 Apr 2021 03:44:29 +0000
From: Billy Tsai <billy_tsai@...eedtech.com>
To: Rob Herring <robh@...nel.org>
CC: "lee.jones@...aro.org" <lee.jones@...aro.org>,
"joel@....id.au" <joel@....id.au>,
"andrew@...id.au" <andrew@...id.au>,
"thierry.reding@...il.com" <thierry.reding@...il.com>,
"u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
"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>,
BMC-SW <BMC-SW@...eedtech.com>
Subject: Re: [v2 1/2] dt-bindings: Add bindings for aspeed pwm-tach and pwm.
Hi Rob,
On 2021/4/15, 6:16 AM,Rob Herringwrote:
On Wed, Apr 14, 2021 at 06:49:38PM +0800, Billy Tsai wrote:
>> This patch adds device bindings for aspeed pwm-tach device which is a
>> multi-function device include pwn and tach function and pwm device which
>> should be the sub-node of pwm-tach device.
>>
>> Signed-off-by: Billy Tsai <billy_tsai@...eedtech.com>
>> Change-Id: I18d9dea14c3a04e1b7e38ffecd49d45917b9b545
>
>Drop
>
>> ---
>> .../bindings/mfd/aspeed,ast2600-pwm-tach.yaml | 60 +++++++++++++++++++
>> .../bindings/pwm/aspeed,ast2600-pwm.yaml | 44 ++++++++++++++
>> 2 files changed, 104 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
>> create mode 100644 Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.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..eaf8bdf8d44e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
>> @@ -0,0 +1,60 @@
>> +# 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 Device Tree Bindings
>> +
>> +description: |
>> + The PWM Tach controller is represented as a multi-function device which
>> + includes:
>> + PWM
>> + Tach
> But is it really? A PWM and tach sounds like a fan controller. Look at
Our PWM is not only for fans but also used for the motor, led, buzzer, and so on.
So I want to split the function into two devices with a multi-function device.
One for PWM output and one for tach monitor.
> other existing PWM+tach bindings we have for fans.
I didn't see the PWM+tach bindings can you give some example for me, thanks.
>> +
>> +maintainers:
>> + - Billy Tsai <billy_tsai@...eedtech.com>
>> +
>> +properties:
>> + compatible:
>> + items:
>> + - enum:
>> + - aspeed,ast2600-pwm-tach
>> + - const: syscon
>> + - const: simple-mfd
>> + reg:
>> + maxItems: 1
>> + "#address-cells":
>> + const: 1
>> + "#size-cells":
>> + const: 1
>> +
>> +required:
>> + - compatible
>> + - reg
>> + - "#address-cells"
>> + - "#size-cells"
>> +
>> +additionalProperties:
>> + type: object
> As you know the 2 node names, they should be documented. However, see
> below.
>> +
>> +examples:
>> + - |
>> + pwm_tach: pwm_tach@...10000 {
>> + compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd";
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + reg = <0x1e610000 0x100>;
>> +
>> + pwm: pwm@0 {
>> + compatible = "aspeed,ast2600-pwm";
>> + #pwm-cells = <3>;
>> + reg = <0x0 0x100>;
>> + };
>> +
>> + tach: tach@1 {
>> + compatible = "aspeed,ast2600-tach";
>> + reg = <0x0 0x100>;
> You have 2 nodes at the same address. Not valid.
Our pwm and tach is used the same base address and the offset is like below:
PWM0 used 0x0 0x4, Tach0 used 0x8 0xc
PWM1 used 0x10 0x14, Tach1 used 0x18 0x1c
...
I will remove the reg property from pwm and tach node and remove the "#address-cells" and
"#size-cells" from the parent node.
>> + };
> There's no real need for 2 child nodes. The parent node can be a PWM
> provider.
However, In our usage, the parent node is a mfd, not a simple PWM device only. I don't want to
combine the different functions with the one device node.
>> + };
>> diff --git a/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml b/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
>> new file mode 100644
>> index 000000000000..97923e68ccb9
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
>> @@ -0,0 +1,44 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +# Copyright (C) 2021 ASPEED, Inc.
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/pwm/aspeed,ast2600-pwm.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: ASPEED AST2600 PWM controller
>> +
>> +maintainers:
>> + - Billy Tsai <billy_tsai@...eedtech.com>
>> +
>> +description: |
>> + The ASPEED PWM controller can support upto 16 PWM outputs.
>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - aspeed,ast2600-pwm
>> +
>> + "#pwm-cells":
>> + const: 3
>> +
>> + reg:
>> + maxItems: 1
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> + - |
>> + // The PWM should be a subnode of a "aspeed,ast2600-pwm-tach" compatible
>> + // node.
>> + pwm_tach: pwm_tach@...10000 {
>> + compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd";
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + reg = <0x1e610000 0x100>;
>> +
>> + pwm: pwm@0 {
>> + compatible = "aspeed,ast2600-pwm";
>> + #pwm-cells = <3>;
>> + reg = <0x0 0x100>;
>> + };
>> + };
>> --
>> 2.25.1
>>
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