linux-kernel - Re: [PATCH v2 2/4] dt-bindings: usb: mtk-xhci: Make all clocks required

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Message-ID: <5f85280ea5fd0d4b445307a13a70c3e3fe552ccf.camel@mediatek.com>
Date:   Sat, 2 Jul 2022 16:24:12 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Rob Herring <robh@...nel.org>,
        "Nícolas F. R. A. Prado" <nfraprado@...labora.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, <kernel@...labora.com>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] dt-bindings: usb: mtk-xhci: Make all clocks
 required

On Fri, 2022-07-01 at 15:37 -0600, Rob Herring wrote:
> On Wed, Jun 29, 2022 at 02:55:46PM -0400, Nícolas F. R. A. Prado
> wrote:
> > On Tue, Jun 28, 2022 at 08:57:45AM +0800, Chunfeng Yun wrote:
> > > Hi Nícolas,
> > > 
> > > On Thu, 2022-06-23 at 15:37 -0400, Nícolas F. R. A. Prado wrote:
> > > > All of the clocks listed in the binding are always wired to the
> > > > XHCI
> > > > controller hardware blocks on all SoCs. The reason some clocks
> > > > were
> > > > made
> > > > optional in the binding was to account for the fact that
> > > > depending on
> > > > the SoC, some of the clocks might be fixed (ie not controlled
> > > > by
> > > > software).
> > > > 
> > > > Given that the devicetree should represent the hardware, make
> > > > all
> > > > clocks
> > > > required in the binding. Subsequent patches will make the DTS
> > > > changes
> > > > to
> > > > specify fixed-clocks for the clocks that aren't controllable.
> > > > 
> > > > Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> > > > 
> > > > ---
> > > > 
> > > > Changes in v2:
> > > > - Undid clock list changes that allowed middle clocks to be
> > > > missing
> > > > from
> > > >   v1 and made all clocks required instead
> > > > - Rewrote commit message and title
> > > > 
> > > >  Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml |
> > > > 4 +
> > > > ---
> > > >  1 file changed, 1 insertion(+), 3 deletions(-)
> > > > 
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/usb/mediatek,mtk-
> > > > xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-
> > > > xhci.yaml
> > > > index 63cbc2b62d18..1444d18ef9bc 100644
> > > > --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-
> > > > xhci.yaml
> > > > +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-
> > > > xhci.yaml
> > > > @@ -67,7 +67,6 @@ properties:
> > > >      maxItems: 1
> > > >  
> > > >    clocks:
> > > > -    minItems: 1
> > > >      items:
> > > >        - description: Controller clock used by normal mode
> > > >        - description: Reference clock used by low power mode
> > > > etc
> > > > @@ -76,9 +75,8 @@ properties:
> > > >        - description: controller clock
> > > >  
> > > >    clock-names:
> > > > -    minItems: 1
> > > >      items:
> > > > -      - const: sys_ck  # required, the following ones are
> > > > optional
> > > > +      - const: sys_ck
> > > >        - const: ref_ck
> > > >        - const: mcu_ck
> > > >        - const: dma_ck
> > > 
> > > This patch causes more check warning, I prefer to leave dt-
> > > bindings
> > > unchanged, but just fix mt8195's dts warning instead, thanks a
> > > lot
> > 
> > Hi Chunfeng,
> > 
> > the warnings reported by Rob's bot only happen if patches 3 and 4
> > aren't applied
> > to adapt the devicetrees. They are ABI breaking changes, but I
> > understood this
> > as the desired solution from the discussion we had with Krzysztof
> > on v1 [1].
> 
> The warnings have nothing to do with patches 3 and 4 as those are
> for 
> dts files. It's examples in bindings that are the problem.
Yes, I mean almost all existing dts supporting mtk-xhci will also cause
similar warnings, as changes in patches 3, 4;

It seems less flexible to make all clock required, not only changes all
existing ones but also need more changes if additional clock is added.

> 
> Rob