RE: [PATCH v28 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and enable-dma properties

Ryan Chen
2026-03-31T06:59:27Z

> Subject: Re: [PATCH v28 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and enable-dma properties
>
> On Mon, Mar 30, 2026 at 04:21:47PM +0800, Ryan Chen wrote:
> > Add aspeed,enable-dma boolean property to indicate that DMA is
> > available for transfers on this I2C bus.
> >
> > Also add the aspeed,global-regs phandle to reference the AST2600
> > global registers syscon node, containing the SoC-common I2C register
> > set.
> >
> > These properties apply only to the AST2600 binding. Legacy DTs remain
> > unchanged.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> > ---
> > Changes in v28:
> > - update commit message correspond with aspeed,enable-dma.
> > - remove aspeed,transfer-mode and add aspeed,enable-dma property and
> > description.
> > - Fix aspeed,enable-dma description to reflect hardware capability rather
> > than software behavior
> > Changes in v27:
> > - change aspeed,transfer-mode to aspeed,enable-dma.
> > ---
> > .../devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml | 12
> ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > index de2c359037da..67b23d1a4cec 100644
> > --- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > +++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > @@ -37,6 +37,16 @@ properties:
> > resets:
> > maxItems: 1
> >
> > + aspeed,enable-dma:
> > + type: boolean
> > + description: Indicates this I2C controller instance has DMA capability.
>
> Compatible implies that "I2C controller instance has DMA capability", no?
>
> How two same devices, with exactly the same or compatible programming
> model can have difference in the programming model for DMA (one lacks it)?
>
> Best regards,
> Krzysztof

Thanks your review.

All AST2600 I2C controller instances have DMA hardware.
I will remove the aspeed,enable-dma property and instead expose sysfs
attribute in driver to allow users to enable dma/buffer/byte.