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From:   Mohan Kumar D <mkumard@nvidia.com>
To:     Thierry Reding <thierry.reding@gmail.com>,
        Krzysztof Kozlowski <krzk@kernel.org>
CC:     "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "krzk+dt@kernel.org" <krzk+dt@kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jonathan Hunter <jonathanh@nvidia.com>
Subject: RE: [PATCH] arm64: tegra: Enable hda node for P3737 + P3701
Thread-Topic: [PATCH] arm64: tegra: Enable hda node for P3737 + P3701
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Date:   Mon, 11 Apr 2022 09:56:50 +0000
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Thierry,
Thanks for your explanation.

Krzysztof,=20
Let me know if you still have any concern on the current patch.

-----Original Message-----
From: Thierry Reding <thierry.reding@gmail.com>=20
Sent: Wednesday, March 30, 2022 4:18 PM
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Mohan Kumar D <mkumard@nvidia.com>; robh+dt@kernel.org; krzk+dt@kernel.=
org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Jonathan Hun=
ter <jonathanh@nvidia.com>
Subject: Re: [PATCH] arm64: tegra: Enable hda node for P3737 + P3701

On Fri, Mar 25, 2022 at 10:42:17AM +0100, Krzysztof Kozlowski wrote:
> On 25/03/2022 10:31, Mohan Kumar D wrote:
> >=20
> > On 3/25/2022 12:56 PM, Krzysztof Kozlowski wrote:
> >> External email: Use caution opening links or attachments
> >>
> >>
> >> On 25/03/2022 08:21, Mohan Kumar wrote:
> >>> Add iommus property for hda and enable the node for P3737 + P3701=20
> >>> platform.
> >>>
> >>> Signed-off-by: Mohan Kumar <mkumard@nvidia.com>
> >>> ---
> >>>   arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts | 1 +
> >>>   arch/arm64/boot/dts/nvidia/tegra234.dtsi                      | 1 +
> >>>   2 files changed, 2 insertions(+)
> >>>
> >>> diff --git=20
> >>> a/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts=20
> >>> b/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts
> >>> index 34d6a01ee1c6..156d5d95fde7 100644
> >>> ---=20
> >>> a/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts
> >>> +++ b/arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dt
> >>> +++ s
> >>> @@ -1751,6 +1751,7 @@
> >>>
> >>>                hda@3510000 {
> >>>                        nvidia,model =3D "NVIDIA Jetson AGX Orin=20
> >>> HDA";
> >>> +                     status =3D "okay";
> >> Nodes are enabled by default. Why do you need this?
> > hda node status is set to "disabled" by default in soc dts file=20
> > tegra234.dtsi. The enable is controlled by platform specific dts files.
>=20
> Oh, surprise... why do you override nodes with full path? This is=20
> error-prone and makes any changes (like node name fixing) difficult.
> This should be overridden by label.

I disagree, though I admit that this is probably very subjective. In my exp=
erience label references lead to completely unreadable DTS files.
We've had bad experiences with these kinds of references early on, so at so=
me point we decided to discontinue that method on Tegra.

Reflecting the tree hierarchy in board-level DTS files on the other hand ma=
kes it very clear what you're changing and keeps the board-level DTS quite =
readable.

Fixing node names hasn't been a big problem for us and any potential remain=
ing issues are entirely gone now that we can validate DTS files using dt-sc=
hema.

Thierry