Re: [PATCH v2 1/3] dt-bindings: iio: adc: sophgo,cv18xx-saradc.yaml: Add Sophgo SARADC binding documentation

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
	Conor Dooley <conor@kernel.org>,
	Thomas Bonnefille <thomas.bonnefille@bootlin.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Chen Wang <unicorn_wang@outlook.com>,
	Inochi Amaoto <inochiama@outlook.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	<linux-iio@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <linux-riscv@lists.infradead.org>
Subject: Re: [PATCH v2 1/3] dt-bindings: iio: adc: sophgo,cv18xx-saradc.yaml: Add Sophgo SARADC binding documentation
Date: Tue, 9 Jul 2024 09:27:22 +0200	[thread overview]
Message-ID: <20240709092722.1a3a2482@xps-13> (raw)
In-Reply-To: <20240708165719.000021b9@Huawei.com>

Hi Jonathan,

> > > > * DO use fallback compatibles when devices are the same as or a subset
> > > >   of prior implementations.
> > > > 
> > > > I believe we fall in the "devices are the same" category, so I would
> > > > have myself wrote a similar binding here with a compatible matching
> > > > them all, plus a hardware-implementation-specific compatible as well;
> > > > just in case.    
> > > 
> > > Fallback from one model to another. There is no "another" model here,
> > > but wildcard. There is no such device as cv18xx, right?  
> > 
> > No there is not. But I don't think there is a "base" model either.
> > Just multiple SoCs named cv18<something> with apparently the same ADC.
> > 
> > So actually I guess the discussion here is about the wildcard
> > compatible. It feels strange to me to have no generic compatible either
> > with a wildcard or with a "base" implementation (because there is
> > probably none). So I guess the solution here is to just list a single
> > specific compatible in the end.
> 
> It comes from long experience of silicon vendors not being consistent
> with part naming.

Oh, agreed :-)

>  Far too often we've had a nice generic wild card
> entry and along comes the vendor with a new part in the middle
> of that range that is completely incompatible.  Then we end up with
> people assuming the wildcard means it will work and a bunch of bug
> reports.  Hence no wild cards, just define first supported part as your
> 'base' and go from there.

I see what you mean. I must admit I'm not a big fan of naming
compatibles (and drivers) after a working base rather than a good
enough wildcard, but I do understand your point and kind of agree with
it actually.

> It's even more fun when a vendor driver papers over the differences
> and so it 'works', but the upstream one doesn't.  In extreme case
> because a different driver entirely is required.
> 
> So basically we don't trust silicon vendors :)
> Speaking as someone who works for one - I think that's entirely
> reasonable!!

Haha <3

Thanks (once again) for your valuable inputs!
Miquèl