linux-kernel - Re: [linux-sunxi] [PATCH 01/13] dt-bindings: update the binding for Allwinner H3 DE2 support

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Date:   Wed, 02 Aug 2017 13:02:39 +0800
From:   icenowy@...c.io
To:     jernej.skrabec@...l.net
Cc:     linux-sunxi@...glegroups.com,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [linux-sunxi] [PATCH 01/13] dt-bindings: update the binding for
 Allwinner H3 DE2 support

在 2017-08-02 12:53，Jernej Škrabec 写道：
> Hi Icenowy,
> 
> Dne torek, 01. avgust 2017 ob 15:12:52 CEST je Icenowy Zheng 
> napisal(a):
>> Allwinner H3 features a "Display Engine 2.0".
>> 
>> Add device tree bindings for the following parts:
>> - H3 TCONs
>> - H3 Mixers
>> - H3 Display engine
>> 
>> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
>> ---
>>  .../bindings/display/sunxi/sun4i-drm.txt           | 25
>> ++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 
>> deletions(-)
>> 
>> diff --git 
>> a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt
>> b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt index
>> 2ee6ff0ef98e..92512953943e 100644
>> --- a/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt
>> +++ b/Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt
>> @@ -87,18 +87,17 @@ Required properties:
>>     * allwinner,sun6i-a31-tcon
>>     * allwinner,sun6i-a31s-tcon
>>     * allwinner,sun8i-a33-tcon
>> +   * allwinner,sun8i-h3-tcon
>>     * allwinner,sun8i-v3s-tcon
>>   - reg: base address and size of memory-mapped region
>>   - interrupts: interrupt associated to this IP
>>   - clocks: phandles to the clocks feeding the TCON. Three are needed:
>>     - 'ahb': the interface clocks
>> -   - 'tcon-ch0': The clock driving the TCON channel 0
>>   - resets: phandles to the reset controllers driving the encoder
>>     - "lcd": the reset line for the TCON channel 0
>> 
>>   - clock-names: the clock names mentioned above
>>   - reset-names: the reset names mentioned above
>> - - clock-output-names: Name of the pixel clock created
>> 
>>  - ports: A ports node with endpoint definitions as defined in
>>    Documentation/devicetree/bindings/media/video-interfaces.txt. The
>> @@ -112,7 +111,23 @@ Required properties:
>>    channel the endpoint is associated to. If that property is not
>>    present, the endpoint number will be used as the channel number.
>> 
>> -On SoCs other than the A33 and V3s, there is one more clock required:
>> +For the following compatibles:
>> +   * allwinner,sun5i-a13-tcon
>> +   * allwinner,sun6i-a31-tcon
>> +   * allwinner,sun6i-a31s-tcon
>> +   * allwinner,sun8i-a33-tcon
>> +   * allwinner,sun8i-v3s-tcon
>> +there is one more clock and one more property required:
>> + - clocks:
>> +   - 'tcon-ch0': The clock driving the TCON channel 0
>> + - clock-output-names: Name of the pixel clock created
>> +
>> +For the following compatibles:
>> +   * allwinner,sun5i-a13-tcon
>> +   * allwinner,sun6i-a31-tcon
>> +   * allwinner,sun6i-a31s-tcon
>> +   * allwinner,sun8i-h3-tcon
>> +there is one more clock required:
>>     - 'tcon-ch1': The clock driving the TCON channel 1
>> 
>>  DRC
>> @@ -207,6 +222,8 @@ supported.
>>  Required properties:
>>    - compatible: value must be one of:
>>      * allwinner,sun8i-v3s-de2-mixer
>> +    * allwinner,sun8i-h3-de2-mixer0
>> +    * allwinner,sun8i-h3-de2-mixer1
> 
> About that, I concur with Maxime here, plane number properties would be
> better. If we don't do this now, we will never have it.

But I still prefer different compatibles, as the capabilities are 
already
proven to be different between mixer0 and mixer1, and furtherly we 
cannot
promise Allwinner won't add more functions only available at mixer0.

Then we will be trapped into a situation that we describe more and more
functions via properties, but they should be encoded into the 
compatible.

> 
> Reference:
> http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/512902.html
> 
> Regards,
> Jernej