Message-ID: <beb0a83b-06f3-44c8-9b55-2903021e9d83@microchip.com>
Date: Wed, 17 Jan 2024 01:58:48 +0000
From: <Dharma.B@...rochip.com>
To: <krzysztof.kozlowski@...aro.org>, <sam@...nborg.org>,
	<bbrezillon@...nel.org>, <maarten.lankhorst@...ux.intel.com>,
	<mripard@...nel.org>, <tzimmermann@...e.de>, <airlied@...il.com>,
	<daniel@...ll.ch>, <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
	<conor+dt@...nel.org>, <Nicolas.Ferre@...rochip.com>,
	<alexandre.belloni@...tlin.com>, <claudiu.beznea@...on.dev>,
	<dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<lee@...nel.org>, <thierry.reding@...il.com>,
	<u.kleine-koenig@...gutronix.de>, <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH 1/3] dt-bindings: display: convert Atmel's HLCDC to DT
 schema

Hi Krzysztof,

On 10/01/24 4:09 pm, Krzysztof Kozlowski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 10/01/2024 11:25, Dharma Balasubiramani wrote:
>> Convert the existing DT binding to DT schema of the Atmel's HLCDC display
>> controller.
>>
>> Signed-off-by: Dharma Balasubiramani <dharma.b@...rochip.com>
>> ---
>>   .../display/atmel/atmel,hlcdc-dc.yaml         | 133 ++++++++++++++++++
>>   .../bindings/display/atmel/hlcdc-dc.txt       |  75 ----------
>>   2 files changed, 133 insertions(+), 75 deletions(-)
>>   create mode 100644 Documentation/devicetree/bindings/display/atmel/atmel,hlcdc-dc.yaml
>>   delete mode 100644 Documentation/devicetree/bindings/display/atmel/hlcdc-dc.txt
>>
>> diff --git a/Documentation/devicetree/bindings/display/atmel/atmel,hlcdc-dc.yaml b/Documentation/devicetree/bindings/display/atmel/atmel,hlcdc-dc.yaml
>> new file mode 100644
>> index 000000000000..49ef28646c48
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/atmel/atmel,hlcdc-dc.yaml
>> @@ -0,0 +1,133 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +# Copyright (C) 2024 Microchip Technology, Inc. and its subsidiaries
> 
> What about original copyrights from TXT file? Although conversion is
> quite independent, I could imagine some lawyer would call it a
> derivative work of original TXT.
> 
> If you decide to add explicit copyrights (which anyway I do not
> understand why), then please make it signed off by some of your lawyers
> to be sure that you really claim that, in respect of other people
> copyrights.
I omitted it in v2, but given the approval from Conor and Alexandre to 
include the copyrights, I will reintroduce it in v3.
> 
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/display/atmel/atmel,hlcdc-dc.yaml#
> 
> Filename like compatible
I modified it in v2.
> 
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Atmel's HLCDC (High LCD Controller) DRM driver
> 
> Driver as Linux driver? Not suitable for bindings, so please drop.
Done.
> 
>> +
>> +maintainers:
>> +  - Nicolas Ferre <nicolas.ferre@...rochip.com>
>> +  - Alexandre Belloni <alexandre.belloni@...tlin.com>
>> +  - Claudiu Beznea <claudiu.beznea@...on.dev>
>> +
>> +description: |
>> +  Device-Tree bindings for Atmel's HLCDC DRM driver. The Atmel HLCDC Display
> 
> Drop entire first sentence and instead describe hardware.
Done.
> 
>> +  Controller is a subdevice of the HLCDC MFD device.
>> +  # See ../../mfd/atmel,hlcdc.yaml for more details.
> 
> Full paths please.
Considering that the MFD's YAML comes after this patch, I have decided 
to remove it here.
> 
>> +
>> +properties:
>> +  compatible:
>> +    const: atmel,hlcdc-display-controller
>> +
>> +  pinctrl-names:
>> +    const: default
>> +
>> +  pinctrl-0: true
> 
> Why do you need these two? Are they really required?
No, I removed it in v2.
> 
>> +
>> +  '#address-cells':
>> +    const: 1
>> +
>> +  '#size-cells':
>> +    const: 0
>> +
>> +  port@0:
>> +    $ref: /schemas/graph.yaml#/$defs/port-base
>> +    unevaluatedProperties: false
>> +    description:
>> +      Output endpoint of the controller, connecting the LCD panel signals.
>> +
>> +    properties:
>> +      '#address-cells':
>> +        const: 1
>> +
>> +      '#size-cells':
>> +        const: 0
>> +
>> +      reg:
>> +        maxItems: 1
>> +
>> +      endpoint:
>> +        $ref: /schemas/graph.yaml#/$defs/endpoint-base
> 
> Hm, why do you reference endpoint-base? This looks oddly different than
> all other bindings for such devices, so please explain why.
My apologies, it should be '$ref: /schemas/media/video-interfaces.yaml#' 
I will correct this in v3.
> 
>> +        unevaluatedProperties: false
>> +        description:
>> +          Endpoint connecting the LCD panel signals.
>> +
>> +        properties:
>> +          bus-width:
>> +            description: |
>> +              Any endpoint grandchild node may specify a desired video interface according to
>> +              ../../media/video-interfaces.yaml, specifically "bus-width" whose recognized
> 
> Drop redundant information. Don't you miss some $ref?
Sure, I will drop the description in v3.
> 
> 
>> +              values are <12>, <16>, <18> and <24>, and override any output mode selection
>> +              heuristic, forcing "rgb444","rgb565", "rgb666" and "rgb888" respectively.
>> +            enum: [ 12, 16, 18, 24 ]
>> +
>> +additionalProperties: false
> 
> This goes after required:
Done.
> 
>> +
>> +required:
>> +  - '#address-cells'
>> +  - '#size-cells'
>> +  - compatible
>> +  - pinctrl-names
>> +  - pinctrl-0
>> +  - port@0
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/at91.h>
>> +    #include <dt-bindings/dma/at91.h>
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +    //Example 1
> 
> Drop
Sure.
> 
>> +    hlcdc: hlcdc@...30000 {
> 
> Node names should be generic. See also an explanation and list of
> examples (not exhaustive) in DT specification:
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> 
> 
>> +      compatible = "atmel,sama5d3-hlcdc";
>> +      reg = <0xf0030000 0x2000>;
>> +      interrupts = <36 IRQ_TYPE_LEVEL_HIGH 0>;
>> +      clocks = <&lcdc_clk>, <&lcdck>, <&clk32k>;
>> +      clock-names = "periph_clk","sys_clk", "slow_clk";
> 
> This part does not look related... If this is part of other device,
> usually it is enough to have just one complete example.
Sure, I will have one complete example in mfd binding and drop the other 
example here.
> 
> Also, fix coding style - space after ,
Sure.
> 
>> +
>> +      hlcdc-display-controller {
>> +        compatible = "atmel,hlcdc-display-controller";
>> +        pinctrl-names = "default";
>> +        pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb888>;
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        port@0 {
>> +          #address-cells = <1>;
>> +          #size-cells = <0>;
>> +          reg = <0>;
>> +
>> +          hlcdc_panel_output: endpoint@0 {
>> +            reg = <0>;
>> +            remote-endpoint = <&panel_input>;
>> +          };
>> +        };
>> +      };
>> +
>> +      hlcdc_pwm: hlcdc-pwm {
>> +        compatible = "atmel,hlcdc-pwm";
> 
> How is this related?
Not related here, thanks, removed it in v2.
> 
>> +        pinctrl-names = "default";
>> +        pinctrl-0 = <&pinctrl_lcd_pwm>;
>> +        #pwm-cells = <3>;
>> +      };
>> +    };
>> +  - |
>> +    //Example 2 With a video interface override to force rgb565
>> +    hlcdc-display-controller {
>> +      pinctrl-names = "default";
>> +      pinctrl-0 = <&pinctrl_lcd_base &pinctrl_lcd_rgb565>;
> 
> And how is this? Where is the compatible? Maybe just drop second
> example, what are the differences?
bus-width is the only property that is different between the examples, I 
will drop the example 2 in v3.
> 
> Are you sure your Microchip folks reviewed it before?
I acknowledge my oversight; I should have sought their review 
beforehand. I appreciate your understanding.

-- 
With Best Regards,
Dharma B.
> 
> Best regards,
> Krzysztof
> 

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