Re: [PATCH] spi: dt-bindings: Move 'rx-sample-delay-ns' to spi-peripheral-props.yaml

From: Rob Herring <robh@kernel.org>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: Serge Semin <fancer.lancer@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] spi: dt-bindings: Move 'rx-sample-delay-ns' to spi-peripheral-props.yaml
Date: Thu, 26 May 2022 08:54:04 -0500	[thread overview]
Message-ID: <20220526135404.GA3831942-robh@kernel.org> (raw)
In-Reply-To: <20220526054642.zw44mgw2bd2u5v76@ti.com>

On Thu, May 26, 2022 at 11:16:42AM +0530, Pratyush Yadav wrote:
> Hi Rob,
> 
> On 25/05/22 04:00PM, Rob Herring wrote:
> > SPI bus per device properties must be defined in spi-peripheral-props.yaml
> > for unevaluatedProperties checks to work correctly on device nodes.
> > 
> > This has the side effect of promoting 'rx-sample-delay-ns' to be a
> > common property, but functionally it's no different if it was defined in
> > a Synopsys specific schema file.
> 
> Functionally it is no different, but does this property make sense for 
> other controllers? If not then I don't see why we should pollute the 
> common list with controller-specific ones. For one, this now no longer 
> makes it obvious that this property should only be used with the 
> Synopsys controller. And if you keep making small exceptions for other 
> controllers too, soon the common list will be full of controller 
> properties and it will be a mess finding out what belongs to who.

There's at least one other case already:

  cdns,read-delay:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      Delay for read capture logic, in clock cycles.

Too many common properties is not a problem we have. Too many custom 
properties doing the same thing is the problem.

Rob