linux-kernel - Re: [PATCH 2/4] arm64: dts: ti: k3-j721e*: Cleanup disabled nodes at SoC dtsi level

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Message-ID: <265fdc00-7f5f-48c3-3d99-971ccd466232@ti.com>
Date:   Thu, 5 Nov 2020 09:25:23 +0200
From:   Tomi Valkeinen <tomi.valkeinen@...com>
To:     Nishanth Menon <nm@...com>, Roger Quadros <rogerq@...com>,
        Keerthy <j-keerthy@...com>, Jyri Sarha <jsarha@...com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Tony Lindgren <tony@...mide.com>, Tero Kristo <t-kristo@...com>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/4] arm64: dts: ti: k3-j721e*: Cleanup disabled nodes at
 SoC dtsi level

On 05/11/2020 00:43, Nishanth Menon wrote:
> The device tree standard sets the default node behavior when status
> property as enabled. There are many reasons for doing the same, number
> of strings in device tree, default power management functionality etc
> are few of the reasons.
> 
> In general, after a few rounds of discussions [1] there are few
> options one could take when dealing with SoC dtsi and board dts
> 
> a. SoC dtsi provide nodes as a super-set default (aka enabled) state and
>    to prevent messy board files, when more boards are added per SoC, we
>    optimize and disable commonly un-used nodes in board-common.dtsi
> b. SoC dtsi disables all hardware dependent nodes by default and board
>    dts files enable nodes based on a need basis.
> c. Subjectively pick and choose which nodes we will disable by default
>    in SoC dtsi and over the years we can optimize things and change
>    default state depending on the need.
> 
> While there are pros and cons on each of these approaches, the right
> thing to do will be to stick with device tree default standards and
> work within those established rules. So, we choose to go with option
> (a).
> 
> Lets cleanup defaults of j721e SoC dtsi before this gets more harder
> to cleanup later on and new SoCs are added.
> 
> The only functional difference between the dtb generated is
> status='okay' is no longer necessary for mcasp10 and depends on the
> default state.
> 
> [1] https://lore.kernel.org/linux-arm-kernel/20201027130701.GE5639@atomide.com/
> 
> Fixes: 1c4d35265fb2 ("arm64: dts: ti: k3-j721e-main: Add McASP nodes")
> Fixes: 76921f15acc0 ("arm64: dts: ti: k3-j721e-main: Add DSS node")
> Cc: Jyri Sarha <jsarha@...com>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: Peter Ujfalusi <peter.ujfalusi@...com>
> Cc: Tony Lindgren <tony@...mide.com>
> Signed-off-by: Nishanth Menon <nm@...com>
> ---
>  .../dts/ti/k3-j721e-common-proc-board.dts     | 48 ++++++++++++++++++-
>  arch/arm64/boot/dts/ti/k3-j721e-main.dtsi     | 26 ----------
>  2 files changed, 47 insertions(+), 27 deletions(-)
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...com>

 Tomi

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