Message-ID: <D2A109C6A8BDED08+aMu4H4xap2GSP50w@LT-Guozexi>
Date: Thu, 18 Sep 2025 15:43:27 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Alex Elder <elder@...cstar.com>, Yixun Lan <dlan@...too.org>
Cc: broonie@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, linux-spi@...r.kernel.org,
	devicetree@...r.kernel.org, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, alex@...ti.fr,
	p.zabel@...gutronix.de, spacemit@...ts.linux.dev,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: Re: [PATCH 1/3] dt-bindings: spi: add SpacemiT K1 SPI support

On Wed, Sep 17, 2025 at 09:59:35PM -0500, Alex Elder wrote:
> On 9/17/25 7:16 PM, Yixun Lan wrote:
> > Hi Alex,
> > 
> > On 18:40 Wed 17 Sep     , Alex Elder wrote:
> > > On 9/17/25 6:15 PM, Yixun Lan wrote:
> > > > Hi Alex,
> > > > 
> > > > On 17:07 Wed 17 Sep     , Alex Elder wrote:
> > > > > Add support for the SPI controller implemented by the SpacemiT K1 SoC.
> > > > > 
> > > > > Signed-off-by: Alex Elder <elder@...cstar.com>
> > > > > ---
> > > > >    .../bindings/spi/spacemit,k1-spi.yaml         | 94 +++++++++++++++++++
> > > > >    1 file changed, 94 insertions(+)
> > > > >    create mode 100644 Documentation/devicetree/bindings/spi/spacemit,k1-spi.yaml
> > > > > 
> > > > > diff --git a/Documentation/devicetree/bindings/spi/spacemit,k1-spi.yaml b/Documentation/devicetree/bindings/spi/spacemit,k1-spi.yaml
> > > > > new file mode 100644
> > > > > index 0000000000000..5abd4fe268da9
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/spi/spacemit,k1-spi.yaml
> > ..
> > > > > +
> > > > > +  spacemit,k1-ssp-id:
> > > > > +    description: SPI controller number
> > > > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > > could you explain a little bit why this vendor specific property should
> > > > be introduced? I took a look at the code, and didn't get the reason
> > > > behind.. or what's the problem of simply using "pdev->id"?
> > > 
> > > This property was carried over from the vendor code.  It is
> > inherit from vendor code isn't a valid reason
> > 
> > > optional, and if it isn't specified, the platform device ID (-1)
> > > will be used.  It's just intended to provide a well-defined ID
> > > for a particular SPI controller.
> > > 
> > while looking at the code, it seems you can use alias to map specific id
> > to the spi controller, it even can do non-linear map, something like
> > 	spi0 = &spi3;
> I've never used this before, but yes, it looks like it's exactly
> what I want.  I'll just get rid of the "spacemit,k1-ssp-id" DT
> property entirely.  Easy.
> 
> > plese check of_alias_get_id()
> > 
> > note, I haven't actually verified on board, just look through the code
This is the right API that Alex what to use.
I have verified it in i2c driver.

                - Troy

> > 
> > > > we should really be careful to introduce vendor specific property..
> > > 
> > > If there were a standard way of doing this I'd love to use it.
> 
> Looks like you have told me the standard way of doing this.
> 
> Thank you.
> 
> 					-Alex
> 
> > > 
> > > And if it isn't necessary, please just explain to me why.  I
> > > have no problem removing it.
> > > 
> > on the opposite, please have explicit good reason to introduce vendor
> > speifici property, and if there is generic way, then we shouldn't do it
> > 
> 
> 
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