linux-kernel - Re: [PATCH 5/7] arm64: dts: mediatek: mt6795: Add fixed clocks for 32kHz and 26MHz XOs

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Message-ID: <d78e1936-a0ab-663d-1381-b537bfd7f07d@linaro.org>
Date:   Mon, 16 May 2022 16:51:40 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, robh+dt@...nel.org
Cc:     krzysztof.kozlowski+dt@...aro.org, matthias.bgg@...il.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        konrad.dybcio@...ainline.org, marijn.suijten@...ainline.org,
        martin.botka@...ainline.org, ~postmarketos/upstreaming@...ts.sr.ht,
        phone-devel@...r.kernel.org, paul.bouchara@...ainline.org,
        kernel@...labora.com
Subject: Re: [PATCH 5/7] arm64: dts: mediatek: mt6795: Add fixed clocks for
 32kHz and 26MHz XOs

On 16/05/2022 10:51, AngeloGioacchino Del Regno wrote:

>>
>>
> 
> I should reword the commit description to be clearer, sorry about that: I
> went with "exactly what I've done", but looking at the actual diff, it is
> just a rename. What my brain was ticking on here was about removing clocks
> that didn't really exist (uart_clk is not a fixed clock, etc), and adding
> the ones that do exist.... but then again, the result, casually, is a rename.

Yes, some better explanation would help.

> 
> In any case... no, these clocks are not board-specific for two reasons:
> 1. AFAIK, these fixed clock outputs are from the SoC itself, not from
>     external components placed on the board, and

This would be fine.

> 2. Even if these were from external components, the SoC *needs* these
>     ones to work and any board that doesn't have these fixed XOs simply
>     wouldn't be able to work.

This is common pattern and Mediatek is not different here. In all cases
these are needed by SoC and in (almost?) all cases these should be
provided by board DTS. The DTS describes here the hardware, the board
has the clock thus the board DTS should define it.


Best regards,
Krzysztof