linux-kernel - Re: [PATCH v4 3/4] dt-bindings: display: rockchip: Add schema for RK3588 HDMI TX Controller

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Message-ID: <5813cea2-4890-4fa9-8826-19be5bf3e161@collabora.com>
Date: Wed, 21 Aug 2024 23:38:01 +0300
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Conor Dooley <conor@...nel.org>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Sandy Huang <hjc@...k-chips.com>, Heiko Stübner
 <heiko@...ech.de>, Andy Yan <andy.yan@...k-chips.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Mark Yao <markyao0591@...il.com>,
 Sascha Hauer <s.hauer@...gutronix.de>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
 kernel@...labora.com, Alexandre ARNOUD <aarnoud@...com>,
 Luis de Arquer <ldearquer@...il.com>
Subject: Re: [PATCH v4 3/4] dt-bindings: display: rockchip: Add schema for
 RK3588 HDMI TX Controller

On 8/21/24 6:07 PM, Conor Dooley wrote:
> On Tue, Aug 20, 2024 at 11:12:45PM +0300, Cristian Ciocaltea wrote:
>> On 8/20/24 7:14 PM, Conor Dooley wrote:
>>> On Tue, Aug 20, 2024 at 03:37:44PM +0300, Cristian Ciocaltea wrote:
>>>> On 8/19/24 7:53 PM, Conor Dooley wrote:
>>>>> On Mon, Aug 19, 2024 at 01:29:30AM +0300, Cristian Ciocaltea wrote:
>>>>>> +  rockchip,grf:
>>>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>>>> +    description:
>>>>>> +      Most HDMI QP related data is accessed through SYS GRF regs.
>>>>>> +
>>>>>> +  rockchip,vo1-grf:
>>>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>>>> +    description:
>>>>>> +      Additional HDMI QP related data is accessed through VO1 GRF regs.
>>>>>
>>>>> Why are these required? What prevents you looking up the syscons by
>>>>> compatible?
>>>>
>>>> That is for getting the proper instance:
>>>
>>> Ah, that makes sense. I am, however, curious why these have the same
>>> compatible when they have different sized regions allocated to them.
>>
>> Good question, didn't notice.  I've just checked the TRM and, in both
>> cases, the maximum register offset is within the 0x100 range.  Presumably
>> this is nothing but an inconsistency, as the syscons have been added in
>> separate commits.
> 
> Is that TRM publicly available? I do find it curious that devices sound
> like they have different contents have the same compatible. In my view,
> that is incorrect and they should have unique compatibles if the
> contents (and therefore the programming model) differs.

Don't know if there's an official location to get it from, but a quick
search on internet shows a few repos providing them, e.g. [1].

Comparing "6.14 VO0_GRF Register Description" at pg. 777 with "6.15 VO1_GRF
Register Description" at pg. 786 (from Part1) reveals the layout is mostly
similar, with a few variations though.

[1] https://github.com/FanX-Tek/rk3588-TRM-and-Datasheet

>>
>>>> 	vo0_grf: syscon@...a6000 {
>>>> 		compatible = "rockchip,rk3588-vo-grf", "syscon";
>>>> 		reg = <0x0 0xfd5a6000 0x0 0x2000>;
>>>> 		clocks = <&cru PCLK_VO0GRF>;
>>>> 	};
>>>>
>>>> 	vo1_grf: syscon@...a8000 {
>>>> 		compatible = "rockchip,rk3588-vo-grf", "syscon";
>>>> 		reg = <0x0 0xfd5a8000 0x0 0x100>;
>>>> 		clocks = <&cru PCLK_VO1GRF>;
>>>> 	};
>