Re: [PATCH 1/2] dt-bindings: spi: Add Socionext F_OSPI controller bindings

[Kunihiko Hayashi]

On 2022/11/19 0:36, Mark Brown wrote:
> On Fri, Nov 18, 2022 at 11:16:22PM +0900, Kunihiko Hayashi wrote:
> > On 2022/11/18 20:39, Mark Brown wrote:
> > > On Fri, Nov 18, 2022 at 09:59:03AM +0900, Kunihiko Hayashi wrote:
>
> > > > +  socionext,cs-start-cycle:
> > > > +  socionext,cs-end-cycle:
> > > > +  socionext,cs-deassert-clk-cycle:
>
> > > These are all generic SPI properties so we should add them
> > > generically, on the device rather than the controller since this
> > > is something that might vary per client device.  There was also a
> > > core function spi_set_cs_timing() which was in earlier versions
> > > and is about to get reintroduced.
>
> > So I understand you mean that these properties should be defined like
> > spi-peripheral-props.yaml for the devices.
>
> > If yes, I'll drop these properties once and define our vendor-specific
> > "peripheral-props" in the next series.
>
> Yes, sounds good.

Okay, I'll send simple one in v2.

> > > > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > > +    items:
> > > > +      - description: the number of bytes to transfer
> > > > +        maximum: 4
> > > > +      - description: value to transfer
> > > > +        default: 0
> > > > +      - description: bit-width to transfer
> > > > +        enum: [0, 1, 2, 4, 8]
>
> > > This is also something SPI device should set up, as far as I can
> > > tell this should be set vis spi_mem_op.dummy.nbytes.
>
> > Yes, but the controller also supports dummy cycles, and can send
> > extra bytes before the dummy cycles.
>
> Ah, so this is some additional thing on top of dummy cycles?  I'd
> not realised that.  It probably wants to be added into spi-mem I
> guess.

Yes, however, it's tough to handle with spi-mem and I don't have
any use case, so drop it.

> > > > +  socionext,data-swap-2byte:
> > > > +    description:
> > > > +      Indicates swap byte order per 2-bytes.
> > > > +    type: boolean
> > >
> > > > +  socionext,data-swap-4byte:
> > > > +    description:
> > > > +      Indicates swap byte order per 4-bytes.
> > > > +    type: boolean
>
> > > Again these should be set by the device.  I think these should be
> > > set based on a combination of bits per word and if the host is in
> > > big endian or little endian mode.
>
> > I see. This feature is complicated to use, so I'll not add it here.
>
> That also works, someone can always add additional support later
> when they have a concrete use case.

I understand.

Thank you,

---
Best Regards
Kunihiko Hayashi