Re: [PATCH v27 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties

Rob Herring
2026-03-25T16:52:46Z

On Wed, Mar 25, 2026 at 08:11:54AM +0000, Ryan Chen wrote:
> Hello Jeremy,
> Thanks the review.
>
> > Subject: Re: [PATCH v27 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> > and transfer-mode properties
> >
> > Hi Ryan,
> >
> > > The AST2600 I2C controller supports three transfer modes (byte,
> > > buffer, DMA). Add "aspeed,transfer-mode" so DT can select the
> > > preferred transfer method per controller instance.
> >
> > This patch does not add an aspeed,transfer-mode property.
> Will update use aspeed,enable-dma

[...]

> > > +  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.
> >
> > As we had discussed: this does not define the transfer mode, only whether
> > DMA is available to the peripheral.
> >
> > Why mention the 16 i2c controllers here?
> >
> > Please keep this description simple and relevant to the specific purpose of the
> > property.
>
> Will update with following.
> description: Enable DMA for transfers on this I2C bus.

You still don't understand the distinction. It's not enable, but that
the h/w instance *has* DMA capability or not. It is still up to the OS
what to do with that information.

Rob