Re: [PATCH 18/23] dt-bindings: media: imx258: Add alternate compatible strings

From: Rob Herring <robh@kernel.org>
To: Luigi311 <git@luigi311.com>
Cc: linux-media@vger.kernel.org, dave.stevenson@raspberrypi.com,
	jacopo.mondi@ideasonboard.com, mchehab@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
	shawnguo@kernel.org, s.hauer@pengutronix.de,
	kernel@pengutronix.de, festevam@gmail.com,
	sakari.ailus@linux.intel.com, devicetree@vger.kernel.org,
	imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 18/23] dt-bindings: media: imx258: Add alternate compatible strings
Date: Thu, 28 Mar 2024 15:46:57 -0500	[thread overview]
Message-ID: <20240328204657.GA314523-robh@kernel.org> (raw)
In-Reply-To: <76f999a7-55e0-4676-aa75-8fcd466e046b@luigi311.com>

On Thu, Mar 28, 2024 at 01:16:22PM -0600, Luigi311 wrote:
> On 3/28/24 12:55, Rob Herring wrote:
> > On Wed, Mar 27, 2024 at 05:17:04PM -0600, git@luigi311.com wrote:
> >> From: Dave Stevenson <dave.stevenson@raspberrypi.com>
> >>
> >> There are a number of variants of the imx258 modules that can not
> >> be differentiated at runtime, so add compatible strings for them.
> >> But you are only adding 1 variant.
> 
> I can not speak for Dave but as to why this was added here but looking
> at the imx296 yaml that has something similar where there are multiple
> variants that may not be detectable at run time but does not include
> similar verbiage in the main description. Should I drop this from the
> description so it matches the imx296?

Just change "add compatible strings for them" to "add compatible string 
for the PDAF variant" or something.

> 
> > 
> >>
> >> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> >> Signed-off-by: Luigi311 <git@luigi311.com>
> >> ---
> >>  .../devicetree/bindings/media/i2c/sony,imx258.yaml          | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml b/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> >> index bee61a443b23..c7856de15ba3 100644
> >> --- a/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> >> +++ b/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> >> @@ -14,10 +14,14 @@ description: |-
> >>    type stacked image sensor with a square pixel array of size 4208 x 3120. It
> >>    is programmable through I2C interface.  Image data is sent through MIPI
> >>    CSI-2.
> >> +  There are a number of variants of the sensor which cannot be detected at
> >> +  runtime, so multiple compatible strings are required to differentiate these.
> > 
> > That's more reasoning/why for the patch than description of the h/w.
> > 
> >>  properties:
> >>    compatible:
> >> -    const: sony,imx258
> >> +    - enum:
> >> +        - sony,imx258
> >> +        - sony,imx258-pdaf
> > 
> > How do I know which one to use? Please define what PDAF means somewhere 
> > as well as perhaps what the original/default variant is or isn't.
> 
> Would it make sense to change the properties to include a description like so
> 
> properties:
>   compatible:
>     enum:
>       - sony,imx258
>       - sony,imx258-pdaf
>     description:
>       The IMX258 sensor exists in two different models, a standard variant
>       (IMX258) and a variant with phase detection autofocus (IMX258-PDAF).
>       The camera module does not expose the model through registers, so the
>       exact model needs to be specified.

Looks fine, but I'd move this to the top-level 'description'.

Rob