Re: [PATCH v5 1/2] dt-bindings: i2c: Add support for ASPEED i2Cv2

[Dhananjay Phadke]

On 2/20/2023 7:32 PM, Ryan Chen wrote:
> > > > > +  timeout:
> > > > > +    type: boolean
> > > > > +    description: Enable i2c bus timeout for master/slave (35ms)
> > > > > +
> > > > > +  byte-mode:
> > > > > +    type: boolean
> > > > > +    description: Force i2c driver use byte mode transmit
> > > > > +
> > > > > +  buff-mode:
> > > > > +    type: boolean
> > > > > +    description: Force i2c driver use buffer mode transmit
> > > >
> > > > These three aren't really a property of the hardware, more of the
> > > > intended driver configuration. Do they really belong in the DT?
> > > Sorry, I am confused.
> > > This is hardware controller mode setting for each i2c transfer.
> > > So I add it in property for change different i2c transfer mode.
> > > Is my mis-understand the property setting?
> >
> > It depends what this is configuration is for.
> >
> > Would you set the transfer mode based on the design of the board? Is there
> > something about the physical i2c bus wiring (or some other hardware design
> > choice) that would mean you use one setting over another?
> No, it not depend on board design. It is only for register control for controller transfer behave.
> The controller support 3 different trigger mode for transfer.
> Byte mode: it means step by step to issue transfer.
> Example i2c read, each step will issue interrupt then driver need trigger for next step.
> Sr (start read) | D | D | D | P
> Buffer mode: it means, the data can prepare into buffer register, then Trigger transfer. So Sr D D D P, only have only 1 interrupt handling.
> The DMA mode most like with buffer mode, The differ is data prepare in DRAM, than trigger transfer.

Unless these settings like xfer mode are per i2c bus, it could be just a
module parameter? Not sure anything other than default mode would be
used if DMA mode works for all master/slave transactions.

Regards,
Dhananjay