linux-kernel - Re: [PATCH RESEND] dt-bindings: trivial-devices: Document SPI measurement on LWE boards

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Message-ID: <20250326222702.436f115b@wsk>
Date: Wed, 26 Mar 2025 22:27:02 +0100
From: Lukasz Majewski <lukma@...x.de>
To: Conor Dooley <conor@...nel.org>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Guenter Roeck <linux@...ck-us.net>,
 Noah Wang <noahwang.wang@...look.com>, Michal Simek <michal.simek@....com>,
 Fabio Estevam <festevam@...il.com>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] dt-bindings: trivial-devices: Document SPI
 measurement on LWE boards

Hi Conor,

> On Wed, Mar 26, 2025 at 06:42:40PM +0100, Lukasz Majewski wrote:
> > Hi Conor,
> >   
> > > On Wed, Mar 26, 2025 at 03:09:30PM +0100, Lukasz Majewski wrote:  
> > > > The measurement device on Liebherr's (LWE) boards is used to
> > > > monitor the overall state of the device. It does have SPI
> > > > interface to communicate with Linux host via spidev driver.
> > > > Document the SPI DT binding as trivial SPI device.
> > > > 
> > > > Signed-off-by: Lukasz Majewski <lukma@...x.de>
> > > > ---    
> > > 
> > > You should not do a resend with no explanation as to why.
> > > Additionally, I would like to know why my review on the original
> > > patch was ignored:
> > > https://lore.kernel.org/all/20250225-despair-rural-dc10216005f4@spud/#t
> > >   
> > 
> > I've made a mistake, as I've used the lwe prefix, which is the
> > different branch office for Liebherr.
> > 
> > As we discussed last time - it would be better to use the already
> > present 'lwn' vendor prefix as several other boards from this
> > company use it (display5, bk4, xea, btt3).
> > 
> > And this was apparent, after I've resent the patches. My mistake.
> > 
> > Regarding the comment - on xea, btt the binding would be used, as
> > those two boards (based on imx287) are using it.
> > 
> > Hence, single "trivial device" would be OK.
> > 
> > The v2 of this patch has the proper 'lwn,btt' binding.  
> 
> I'm sorry, I don't understand how this excuses using the same binding
> for different devices.

Ok, so maybe I will just explain how things are on those devices and we
can find some solution.

So we do have two devices - based on imx287: XEA (rev 1,2) and BTT (rev
0,1,2).

We do have a measurement device connected to SPI (on both above
devices). This device has a protocol, which is fully served in user
space (just the /dev/spidevX.Y is required for it).

Hence the 'lwn,btt' can be used for all those measurement devices.

As pointed out by Fabio, there is also 'lwn,bk4-spi' which is totally
different device, with different protocol used.


> 
> >   
> > > Cheers,
> > > Conor.
> > >   
> > > >  Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > > 
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/trivial-devices.yaml
> > > > b/Documentation/devicetree/bindings/trivial-devices.yaml index
> > > > fadbd3c041c8..5d736a9792c2 100644 ---
> > > > a/Documentation/devicetree/bindings/trivial-devices.yaml +++
> > > > b/Documentation/devicetree/bindings/trivial-devices.yaml @@
> > > > -161,6 +161,8 @@ properties:
> > > >            - jedec,spd5118
> > > >              # Linear Technology LTC2488
> > > >            - lineartechnology,ltc2488
> > > > +            # Liebherr on-board measurement SPI device
> > > > +          - lwe,btt
> > > >              # 5 Bit Programmable, Pulse-Width Modulator
> > > >            - maxim,ds1050
> > > >              # 10 kOhm digital potentiometer with I2C interface
> > > > -- 
> > > > 2.39.5
> > > >     
> > 
> > 
> > 
> > 
> > Best regards,
> > 
> > Lukasz Majewski
> > 
> > --
> > 
> > DENX Software Engineering GmbH,      Managing Director: Erika Unter
> > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > lukma@...x.de  
> 
> 




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@...x.de

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