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

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Message-ID: <20240821-stretch-scam-09d7adc08a4c@spud>
Date: Wed, 21 Aug 2024 22:28:55 +0100
From: Conor Dooley <conor@...nel.org>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
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

Cristian, Heiko,

On Wed, Aug 21, 2024 at 11:38:01PM +0300, Cristian Ciocaltea wrote:
> 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.

Page references and everything, thank you very much. I don't think those
two GRFs should have the same compatibles, they're, as you say, similar
but not identical. Seems like a bug to me!

Heiko, what do you think?

> [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>;
> >>>> 	};
> >

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