linux-kernel - RE: 回复: [PATCH v2 1/2] ASoC: dt-bindings: Add bindings for Cadence I2S-MC controller

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Date: Fri, 29 Mar 2024 03:56:30 +0000
From: Xingyu Wu <xingyu.wu@...rfivetech.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, Liam Girdwood
	<lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Claudiu Beznea
	<Claudiu.Beznea@...rochip.com>, Jaroslav Kysela <perex@...ex.cz>, Takashi
 Iwai <tiwai@...e.com>, Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
	<conor.dooley@...rochip.com>
CC: "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"linux-sound@...r.kernel.org" <linux-sound@...r.kernel.org>
Subject:
 RE: 回复: [PATCH v2 1/2] ASoC: dt-bindings: Add bindings for Cadence I2S-MC controller

On 27/03/2024 13:12, Krzysztof Kozlowski wrote:

> On 26/03/2024 14:43, Xingyu Wu wrote:
> >>>>> +
> >>>>> +properties:
> >>>>> +  compatible:
> >>>>> +    enum:
> >>>>> +      - cdns,i2s-mc
> >>>>
> >>>> Why did this appear? Who asked for this? Usually these blocks are
> >>>> not usable on their own.
> >>>
> >>> I wonder if I should keep the original IP compatible. Do I not need it?
> >>
> >> As I said, it is not usable on its own, so unless you have other arguments then
> no.
> >> But my point was that no one asked for this.
> >
> > I want to keep the original IP compatible which can distinguish from the JH8100
> SoC.
> > Can I write it like this:
> > compatible:
> >    enum:
> >           - starfive,jh8100-i2s
> >    const: cdns,i2s-mc
> >
> > and I write this in the DTS:
> > compatible = "starfive,jh8100-i2s", "cdns,i2s-mc";
> 
> Can you provide any rationale for this? I asked "unless you have other
> arguments", so where are the arguments?
> 
> Nothing was explained in patch changelog. Nothing was provided in this email
> thread.

I don't know if I understood what mark said[1]. Is it to keep the original IP and
add other compatible?

[1] https://lore.kernel.org/all/27155281-573c-493d-96fe-1f28ebb0ce5e@sirena.org.uk/

Or should I only keep the compatible 'starfive,jh8110-i2s' and change the
bindings name to same to this compatible?

> 
> >
> >>
> >>>
> >>>>
> >>>>> +      - starfive,jh8100-i2s
> >>>>> +
> >>>>> +  reg:
> >>>>> +    maxItems: 1
> >>>>> +
> >>>>> +  interrupts:
> >>>>> +    description:
> >>>>> +      The interrupt line number for the I2S controller. Add this
> >>>>> +      parameter if the I2S controller that you are using does not
> >>>>> +      using DMA.
> >>>>
> >>>> That's still wrong. You already got comment on this. Either you
> >>>> have interrupt
> >> or not.
> >>>> You do not add interrupts, based on your choice or not of having DMA.
> >>>> Drop the comment.
> >>>
> >>> Do I keep this property and drop this description?
> >>
> >> Drop description. Keep property, if your hardware has interrupts.
> >>
> >
> > Will drop.
> >
> >> ...
> >>
> >>>>
> >>>>> +  - compatible
> >>>>> +  - reg
> >>>>> +  - clocks
> >>>>> +  - clock-names
> >>>>> +  - resets
> >>>>> +
> >>>>> +oneOf:
> >>>>> +  - required:
> >>>>> +      - dmas
> >>>>> +      - dma-names
> >>>>> +  - required:
> >>>>> +      - interrupts
> >>>>
> >>>> This won't work. Provide both interrupts and dmas, and then test your DTS.
> >>>
> >>> I provided both properties in the DTS and test by dtbs_check. Then
> >>> it printed
> >> that:
> >>> 'More than one condition true in one of shema: ...'
> >>
> >> Exactly. Having both properties is a correct DTS. Interrupts do not
> >> disappear just because you decide to describe DMA. It is OS choice
> >> what to use if both are provided.
> >>
> >
> > But this I2S can only use either DMA or interrupts.
> 
> Just like many other components. DTS should reflect hardware. Hardware has
> interrupts and DMA, right?

Yes. The hardware can use interrupts and provide the handshake interface of
DMA to DMA controller. In software, we can choose only one between them.
Do I keep them both in the bindings and provide the selection in the driver?

> 
> >
> > Can I use the config (like SND_SOC_CADENCE_I2S_MC_PCM)  to choose DMA
> > or interrupt if having both them in DTS?
> 
> Don't know, I tend to focus here on bindings.
> 

Best regards,
Xingyu Wu