linux-kernel - RE: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for AST2600-i2cv2

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Message-ID:
 <OS8PR06MB75415E95342F26F576B5CF8AF2C22@OS8PR06MB7541.apcprd06.prod.outlook.com>
Date: Wed, 26 Feb 2025 09:28:20 +0000
From: Ryan Chen <ryan_chen@...eedtech.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: "benh@...nel.crashing.org" <benh@...nel.crashing.org>, "joel@....id.au"
	<joel@....id.au>, "andi.shyti@...nel.org" <andi.shyti@...nel.org>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"andrew@...econstruct.com.au" <andrew@...econstruct.com.au>,
	"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
	"andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-aspeed@...ts.ozlabs.org"
	<linux-aspeed@...ts.ozlabs.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for
 AST2600-i2cv2

> Subject: Re: [PATCH v16 1/3] dt-bindings: i2c: aspeed: support for
> AST2600-i2cv2
> 
> On Mon, Feb 24, 2025 at 01:59:34PM +0800, Ryan Chen wrote:
> > Add ast2600-i2cv2 compatible and aspeed,global-regs, aspeed,enable-dma
> > and description for ast2600-i2cv2.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@...eedtech.com>
> > ---
> >  .../devicetree/bindings/i2c/aspeed,i2c.yaml   | 58 +++++++++++++++++++
> >  1 file changed, 58 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > index 5b9bd2feda3b..356033d18f90 100644
> > --- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > +++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > @@ -44,12 +44,60 @@ properties:
> >      description: frequency of the bus clock in Hz defaults to 100 kHz when
> not
> >        specified
> >
> > +  multi-master:
> > +    type: boolean
> > +    description:
> > +      states that there is another master active on this bus
> 
> Except that this wasn't ever tested...
> 
> Don't duplicate properties. i2c-controller schema has it already.

I will remove it to avoid duplication.
> 
> > +
> > +  aspeed,enable-dma:
> > +    type: boolean
> > +    description: |
> > +      I2C bus enable dma mode transfer.
> > +
> > +      ASPEED ast2600 platform equipped with 16 I2C controllers that
> share a
> > +      single DMA engine. DTS files can specify the data transfer mode
> to/from
> > +      the device, either DMA or programmed I/O. However, hardware
> > + limitations
> 
> so what is byte mode?
I explain in cover, I will add here also. 
aspeed,enable-byte:
Force i2c controller use byte mode transfer. the byte mode transfer
will send i2c data each byte by byte, inlcude address read/write.

> 
> > +      may require a DTS to manually allocate which controller can use
> DMA mode.
> > +      The "aspeed,enable-dma" property allows control of this.
> > +
> > +      In cases where one the hardware design results in a specific
> > +      controller handling a larger amount of data, a DTS would likely
> > +      enable DMA mode for that one controller.
> > +
> > +  aspeed,enable-byte:
> > +    type: boolean
> > +    description: |
> > +      I2C bus enable byte mode transfer.
> 
> No, either this is expressed as lack of dma mode property or if you have three
> modes, then rather some enum (aspeed,transfer-mode ?)

Thanks suggestion, I will using an enum property like aspeed,transfer-mode instead.
> 
> 
> 
> > +
> > +  aspeed,global-regs:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description: The phandle of i2c global register node.
> 
> For what? Same question as usual: do not repeat property name, but say what
> is this used for and what exactly it points to.
> 
> s/i2c/I2C/ but then what is "I2C global register node"? This is how you call your
> device in datasheet?
> 
I do descript in cover, should add into the yaml file ?

aspeed,global-regs: 
This global register is needed, global register is setting for
new clock divide control, and new register set control.

> 
> > +
> >  required:
> >    - reg
> >    - compatible
> >    - clocks
> >    - resets
> >
> > +allOf:
> > +  - $ref: /schemas/i2c/i2c-controller.yaml#
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: aspeed,ast2600-i2cv2
> 
> NAK, undocumented compatible.

Sorry, I should add what kind of document about this compatible?

The cover descripts it, should I add into yaml?


This series add AST2600 i2cv2 new register set driver. The i2cv2 driver
is new register set that have new clock divider option for more flexiable
generation. And also have separate i2c controller and target register
set for control, patch #2 is i2c controller driver only, patch #3 is add
i2c target mode driver.

The legacy register layout is mix controller/target register control
together. The following is add more detail description about new register
layout. And new feature set add for register.
> 
> > +
> > +    then:
> > +      properties:
> > +        reg:
> > +          minItems: 2
> 
> 
> Best regards,
> Krzysztof