linux-kernel - Re: [PATCH 7/9] dt-bindings: spi: mtk-snfi: add two timing delay property

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Message-ID: <f83184ae803dbe0afd37a31a8a83a369a9772880.camel@mediatek.com>
Date:   Tue, 29 Nov 2022 02:50:25 +0000
From:   Xiangsheng Hou (侯祥胜) 
        <Xiangsheng.Hou@...iatek.com>
To:     "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski@...aro.org" <krzysztof.kozlowski@...aro.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "gch981213@...il.com" <gch981213@...il.com>,
        "vigneshr@...com" <vigneshr@...com>,
        "richard@....at" <richard@....at>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Benliang Zhao (赵本亮) 
        <Benliang.Zhao@...iatek.com>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Bin Zhang (章斌) <bin.zhang@...iatek.com>
Subject: Re: [PATCH 7/9] dt-bindings: spi: mtk-snfi: add two timing delay
 property

Hi Krzysztof,

On Mon, 2022-11-28 at 10:04 +0100, Krzysztof Kozlowski wrote:
> On 28/11/2022 03:06, Xiangsheng Hou wrote:
> > add rx-sample-delay and rx-latch-latency property.
> 
> Start sentences with capital letter.
> 
> Here and in commit subject: property->properties
Will be fixed in next series.

> > 
> > --- a/Documentation/devicetree/bindings/spi/mediatek,spi-mtk-
> > snfi.yaml
> > +++ b/Documentation/devicetree/bindings/spi/mediatek,spi-mtk-
> > snfi.yaml
> > @@ -55,6 +55,22 @@ properties:
> >      description: device-tree node of the accompanying ECC engine.
> >      $ref: /schemas/types.yaml#/definitions/phandle
> >  
> > +  rx-sample-delay:
> 
> No, use existing property, don't invent your own stuff - missing unit
> suffix. See spi-peripheral-props.yaml.
Will change to other private property. The read sample delay with
MediaTek SPI NAND controller can be set with values from 0 to 47.
However, it`s difficult to say the unit of each vaule, because the unit
value will be difference with different chip process or different
corner IC.

> > +    description: Rx delay to sample data with this value, the
> > valid
> > +                 values are from 0 to 47. The delay is smaller
> > than
> > +                 the rx-latch-latency.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> Drop $ref.
Will do.

> 
> > +    minItems: 0
> > +    maxItems: 47
> > +    default: 0
> > +
> > +  rx-latch-latency:
> 
> Same problems. Did you check spi-peripheral-props.yaml or other SPI
> controller schemas for such property?
> 
> > +    description: Rx delay to sample data with this value, the
> > value
> > +                 unit is clock cycle.
> 
> I think the unit should be rather time (e.g. us).
> 
Yes, I checked the spi-peripheral-props.yaml and the delay values are
described exactly unit with ns or us. However the unit of MediaTek read
latch latency is clock cycle and it`s difference with different clock
frequency.

> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 1, 2, 3]
> > +    default: 0
> > +
> >  required:
> >    - compatible
> >    - reg
> 
Best regards,
Xiangsheng Hou