Re: [PATCH v2 2/3] arm64: dts: rockchip: Fix vdec register blocks order on RK3576

From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
To: Krzysztof Kozlowski <krzk@kernel.org>,
	Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Cc: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>,
	Detlev Casanova	 <detlev.casanova@collabora.com>,
	Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
	 Mauro Carvalho Chehab	 <mchehab@kernel.org>,
	Hans Verkuil <hverkuil@kernel.org>,
	kernel@collabora.com, 	devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
		linux-rockchip@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Conor Dooley	 <conor.dooley@microchip.com>,
	linux-media@vger.kernel.org
Subject: Re: [PATCH v2 2/3] arm64: dts: rockchip: Fix vdec register blocks order on RK3576
Date: Tue, 24 Feb 2026 08:17:44 -0500	[thread overview]
Message-ID: <366daf706b5dc3942e3340f29151ece1f49460e0.camel@collabora.com> (raw)
In-Reply-To: <20260224-glaring-poetic-goshawk-b44d7b@quoll>

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Hi,

Le mardi 24 février 2026 à 08:22 +0100, Krzysztof Kozlowski a écrit :
> On Mon, Feb 23, 2026 at 09:49:50PM +0200, Cristian Ciocaltea wrote:
> > When building device trees for the RK3576 based boards, DTC shows the
> > following complaint:
> > 
> >   rk3576.dtsi:1282.30-1304.5: Warning (simple_bus_reg): /soc/video-codec@27b00000: simple-bus unit address format error, expected "27b00100"
> 
> So you need to fix the unit address. This is what the warning tells you.

The unit address is where the register range starts. Picking a random point
inside the range is just bad idea. For anyone that uses spec to develop these
drivers and device tree, its just plain difficult and error prone.

> 
> > 
> > Provide the register blocks in the expected address-based order.
> > 
> > Fixes: da0de806d8b4 ("arm64: dts: rockchip: Add the vdpu383 Video Decoder on rk3576")
> > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3576.dtsi | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576.dtsi b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
> > index 49ccdf12ef7e..45eb0d053a6f 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
> > @@ -1281,10 +1281,10 @@ gpu: gpu@27800000 {
> >  
> >  		vdec: video-codec@27b00000 {
> >  			compatible = "rockchip,rk3576-vdec";
> > -			reg = <0x0 0x27b00100 0x0 0x500>,
> > -			      <0x0 0x27b00000 0x0 0x100>,
> > +			reg = <0x0 0x27b00000 0x0 0x100>,
> > +			      <0x0 0x27b00100 0x0 0x500>,
> >  			      <0x0 0x27b00600 0x0 0x100>;
> 
> The main block, so probably the lowest address as in unit address,
> should be used, but this ship has sailed. You shipped this DTS, because
> the order of items is FIXED. Your binding change is clearly incorrect
> and ABI break without explanation and without reason, so you cannot use
> such as an argument here.

Its not released yet.

> You cannot change it without impact, so just fix the unit address.

I completely disagree with that.

Nicolas

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