linux-kernel - Re: [PATCH v1 1/2] dt-bindings: dsp: mediatek: Add default clock sources for mt8186 dsp

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Message-ID: <29345c6f3497b3470d627fc9f09bc99216971def.camel@mediatek.com>
Date:   Thu, 3 Nov 2022 02:27:45 +0000
From:   TingHan Shen (沈廷翰) 
        <TingHan.Shen@...iatek.com>
To:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        YC Hung (洪堯俊) <yc.hung@...iatek.com>,
        "kai.vehmanen@...ux.intel.com" <kai.vehmanen@...ux.intel.com>,
        "pierre-louis.bossart@...ux.intel.com" 
        <pierre-louis.bossart@...ux.intel.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "yung-chuan.liao@...ux.intel.com" <yung-chuan.liao@...ux.intel.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "peter.ujfalusi@...ux.intel.com" <peter.ujfalusi@...ux.intel.com>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "daniel.baluta@....com" <daniel.baluta@....com>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "ranjani.sridharan@...ux.intel.com" 
        <ranjani.sridharan@...ux.intel.com>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "sound-open-firmware@...a-project.org" 
        <sound-open-firmware@...a-project.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v1 1/2] dt-bindings: dsp: mediatek: Add default clock
 sources for mt8186 dsp

On Wed, 2022-11-02 at 10:13 +0100, AngeloGioacchino Del Regno wrote:
> Il 01/11/22 07:11, Tinghan Shen ha scritto:
> > Add the default clock sources used by mt8186 dsp.
> > 
> > Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
> > ---
> >   .../devicetree/bindings/dsp/mediatek,mt8186-dsp.yaml | 12 +++++++++---
> >   1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/dsp/mediatek,mt8186-dsp.yaml b/Documentation/devicetree/bindings/dsp/mediatek,mt8186-dsp.yaml
> > index 3e63f79890b4..4cc0634c876b 100644
> > --- a/Documentation/devicetree/bindings/dsp/mediatek,mt8186-dsp.yaml
> > +++ b/Documentation/devicetree/bindings/dsp/mediatek,mt8186-dsp.yaml
> > @@ -35,11 +35,15 @@ properties:
> >       items:
> >         - description: mux for audio dsp clock
> >         - description: mux for audio dsp local bus
> > +      - description: default clock source for dsp local bus
> > +      - description: default clock source for dsp core
> >   
> >     clock-names:
> >       items:
> >         - const: audiodsp
> >         - const: adsp_bus
> > +      - const: mainpll_d2_d2
> > +      - const: clk26m
> >   
> >     power-domains:
> >       maxItems: 1
> > @@ -82,9 +86,11 @@ examples:
> >                 <0x1068f000 0x1000>;
> >           reg-names = "cfg", "sram", "sec", "bus";
> >           clocks = <&topckgen CLK_TOP_AUDIODSP>,
> > -                 <&topckgen CLK_TOP_ADSP_BUS>;
> > -        clock-names = "audiodsp",
> > -                      "adsp_bus";
> > +                 <&topckgen CLK_TOP_ADSP_BUS>,
> > +                 <&topckgen CLK_TOP_MAINPLL_D2_D2>,
> > +                 <&clk26m>;
> > +        clock-names = "audiodsp", "adsp_bus",
> > +                      "mainpll_d2_d2", "clk26m";
> 
> You are assigning those clocks just to be able to call clk_set_parent() in
> the DSP mt8186-clk driver... and that's not necessary, nor it is the best
> way of doing what you're trying to.
> 
> In reality, you don't need to add new clocks and you don't need to manage
> that into the driver, as you can simply assign clock parents in devicetree
> ... like:
> 
> assigned-clocks = <&topckgen CLK_TOP_AUDIODSP>, <&topckgen CLK_TOP_ADSP_BUS>;
> assigned-clock-parents = <&clk26m>, <&topckgen CLK_TOP_MAINPLL_D2_D2>;
> 
> without any clk_set_parent() call in the driver.
> 
> When the driver will call clk_prepare_enable() for top_audiodsp and/or for
> top_adsp_bus, the assigned parents' refcount will also be increased (and
> if the parent clock is not enabled, the clk framework will enable it).
> 
> Regards,
> Angelo
> 
Hi Angelo,

Thank you very much!

I will abandon this series.
Thank you!


-- 
Best regards,
TingHan