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

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Message-ID: <400a464f-8d5b-9979-fb77-d939ac3bc994@ti.com>
Date:   Mon, 9 Nov 2020 09:49:26 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Nishanth Menon <nm@...com>
CC:     Roger Quadros <rogerq@...com>, Keerthy <j-keerthy@...com>,
        Jyri Sarha <jsarha@...com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Tero Kristo <t-kristo@...com>, <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 06/11/2020 23.46, Nishanth Menon wrote:
> On 13:32-20201106, Peter Ujfalusi wrote:
> [...]
>>>
>>>>
>>>>> default power management functionality etc
>>>>
>>>> Right, so how does that helps with devices present in the SoC, but no
>>>> node at all? First thing which comes to mind is AASRC, we don't have
>>>> Linux driver for it (and no DT binding document), but that does not mean
>>>> that it is not present. How PM would take that into account?
>>>
>>> I think we are mixing topics here -> I was stating the motivation why
>>> devicetree chose such as default.
>>
>> I don't question the fact that 'okay' is the default status if it is not
>> explicitly present. There is no better default than that.
> 
> ^^ -> Alright, that is all we are trying to do here: defaults in the
> SoC.dtsi and specific cleanups (firmware reserved / board unused
> disables) be done in a common board.dtsi (for now, there is no such
> specific need, I guess).

The default is what it is: default choice which suits most of the nodes.

If the node is not complete in it's present form then it is not in it's
default state. imho.

>>> Alright - what do we suggest we do?
>>
>> Not sure, I'm 'whatever' after [1] makes it to mainline or next.
> [....]
>> [1]
>> https://lore.kernel.org/alsa-devel/20201106072551.689-1-peter.ujfalusi@ti.com/
> 
> 
> I don't see the relationship between the series.. I think this series
> brings no change in dtb, hence with OR without your driver cleanup
> series, there is no practical regressions.

This series opens up the possibility of nodes leaking to dtb with known
broken state and the driver should have a better strategy than 'works by
luck' to handle it ;)

>>
>>> Tony, Rob - I need some guidance here.
>>
>> I'm fine whatever way we take, but I think it is up to you to make the
>> call as the maintainer of the TI dts files... ;)
> 
> Yep - I have'nt seen a reason yet that must cause us to change from the
> Device tree default approach in our debates.

Imho 'disabled' is the default for nodes like McASP as it is:
"Indicates that the device is not presently operational, but it might
become operational in the future" (for example, needed properties added
to the node).

>>>> There is no such a tag, but:
>>>> whatever-by: Peter Ujfalusi <peter.ujfalusi@...com>
>>>
>>> OK - I have no idea how B4 or patchworks pick that one as :D
>>
>> If we take this road, than I'm okay with it, but I'm going to take
>> silent protest (not sending acked-by or revired-by).
>> That should not stop you doing what you believe is best for the future!
> 
> OK - thanks for your review and the discussions, always appreciate
> getting our views out there.
> 
> if there are no other comments, I will try and post a v2 over the
> weekend.

OK

- Péter

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