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Date: Fri, 5 Apr 2024 17:24:11 +0100
From: Conor Dooley <conor@kernel.org>
To: Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc: git@luigi311.com, linux-media@vger.kernel.org,
	jacopo.mondi@ideasonboard.com, mchehab@kernel.org, robh@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,
	pavel@ucw.cz, phone-devel@vger.kernel.org
Subject: Re: [PATCH v3 18/25] dt-bindings: media: imx258: Add alternate
 compatible strings
Message-ID: <20240405-affair-cruelly-a7e9d23b597c@spud>
References: <20240403150355.189229-1-git@luigi311.com>
 <20240403150355.189229-19-git@luigi311.com>
 <20240403-vista-defendant-ebadbaa52059@spud>
 <CAPY8ntC9SHJ6Ma17s0Vf2coB-0NUk-xgCLK9KCkxFMuXKHXNwg@mail.gmail.com>
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On Fri, Apr 05, 2024 at 11:25:50AM +0100, Dave Stevenson wrote:
> Hi Conor
>=20
> On Wed, 3 Apr 2024 at 17:14, Conor Dooley <conor@kernel.org> wrote:
> >
> > On Wed, Apr 03, 2024 at 09:03:47AM -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 the
> > > PDAF variant.
> > >
> > > Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> > > Signed-off-by: Luis Garcia <git@luigi311.com>
> > > ---
> > >  .../devicetree/bindings/media/i2c/sony,imx258.yaml       | 9 +++++++=
--
> > >  1 file changed, 7 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/media/i2c/sony,imx258.=
yaml b/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> > > index bee61a443b23..c978abc0cdb3 100644
> > > --- a/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> > > +++ b/Documentation/devicetree/bindings/media/i2c/sony,imx258.yaml
> > > @@ -13,11 +13,16 @@ description: |-
> > >    IMX258 is a diagonal 5.867mm (Type 1/3.06) 13 Mega-pixel CMOS acti=
ve pixel
> > >    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.
> > > +  CSI-2. The sensor exists in two different models, a standard varia=
nt
> > > +  (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.
> > >
> > >  properties:
> > >    compatible:
> > > -    const: sony,imx258
> > > +    enum:
> > > +      - sony,imx258
> > > +      - sony,imx258-pdaf
> >
> > Does the pdaf variant support all of the features/is it register
> > compatible with the regular variant? If it is, the regular variant
> > should be a fallback compatible.
>=20
> It has the same register set, but certain registers have to be
> programmed differently so that the image is corrected for the
> partially shielded pixels used for phase detect auto focus (PDAF).
> Either compatible will "work" on either variant of the module, but
> you'll get weird image artifacts when using the wrong one.

To paraphase, a fallback compatible is not suitable.

Thanks Dave,
Conor.

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