linux-kernel - Re: [PATCH v2 1/4] media: i2c: imx290: Limit analogue gain according to module

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Message-ID: <CAPY8ntCeYOtBhEKCcygsT-aAHJ8rxo5qP0NdjE9DMJmHCxZzsA@mail.gmail.com>
Date: Thu, 5 Dec 2024 15:37:01 +0000
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Alexander Stein <alexander.stein@...tq-group.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, linux-media@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/4] media: i2c: imx290: Limit analogue gain according
 to module

Hi Alexander

On Thu, 5 Dec 2024 at 15:22, Alexander Stein
<alexander.stein@...tq-group.com> wrote:
>
> Hi Dave,
>
> Am Mittwoch, 20. November 2024, 20:17:03 CET schrieb Dave Stevenson:
> > The imx327 only supports up to 29.4dB of analogue gain, vs
> > the imx290 going up to 30dB. Both are in 0.3dB steps.
>
> While I agree for 30dB on imx290, my (maybe outdated) Rev0.2 datasheet says
> up to 27dB in 0.3dB steps.

For IMX327, I have revision E17Z06B93 2019/03/25.

The revision control section for Rev0.3 lists
Page 1: "Correction: Max analog gain 27dB - 29.4dB"
Page 74: "Correction: Max Gain 69dB -> 71.4dB"

The graph in "Gain Adjustment Function" (page 74) also shows values
above 27dB as being purely analogue gain. Certainly 0x62 is red for
analogue, which would be a gain of 29.4dB. The next dot is 0x64 (30dB)
and blue, so we have to trust the text for 0x63 being 29.4dB analogue
and 0.3dB digital gain.

So I'm happy that the limit is 29.4dB.

  Dave

> Despite that this change looks good.
>
> Best regards,
> Alexander
>
> > As we now have model specific config, fix this mismatch,
> > and delete the comment referencing it.
> >
> > Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > ---
> >  drivers/media/i2c/imx290.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> > index ee698c99001d..da654deb444a 100644
> > --- a/drivers/media/i2c/imx290.c
> > +++ b/drivers/media/i2c/imx290.c
> > @@ -176,6 +176,7 @@ struct imx290_model_info {
> >       enum imx290_colour_variant colour_variant;
> >       const struct cci_reg_sequence *init_regs;
> >       size_t init_regs_num;
> > +     unsigned int max_analog_gain;
> >       const char *name;
> >  };
> >
> > @@ -876,14 +877,10 @@ static int imx290_ctrl_init(struct imx290 *imx290)
> >        * up to 72.0dB (240) add further digital gain. Limit the range to
> >        * analog gain only, support for digital gain can be added separately
> >        * if needed.
> > -      *
> > -      * The IMX327 and IMX462 are largely compatible with the IMX290, but
> > -      * have an analog gain range of 0.0dB to 29.4dB and 42dB of digital
> > -      * gain. When support for those sensors gets added to the driver, the
> > -      * gain control should be adjusted accordingly.
> >        */
> >       v4l2_ctrl_new_std(&imx290->ctrls, &imx290_ctrl_ops,
> > -                       V4L2_CID_ANALOGUE_GAIN, 0, 100, 1, 0);
> > +                       V4L2_CID_ANALOGUE_GAIN, 0,
> > +                       imx290->model->max_analog_gain, 1, 0);
> >
> >       /*
> >        * Correct range will be determined through imx290_ctrl_update setting
> > @@ -1441,18 +1438,21 @@ static const struct imx290_model_info imx290_models[] = {
> >               .colour_variant = IMX290_VARIANT_COLOUR,
> >               .init_regs = imx290_global_init_settings_290,
> >               .init_regs_num = ARRAY_SIZE(imx290_global_init_settings_290),
> > +             .max_analog_gain = 100,
> >               .name = "imx290",
> >       },
> >       [IMX290_MODEL_IMX290LLR] = {
> >               .colour_variant = IMX290_VARIANT_MONO,
> >               .init_regs = imx290_global_init_settings_290,
> >               .init_regs_num = ARRAY_SIZE(imx290_global_init_settings_290),
> > +             .max_analog_gain = 100,
> >               .name = "imx290",
> >       },
> >       [IMX290_MODEL_IMX327LQR] = {
> >               .colour_variant = IMX290_VARIANT_COLOUR,
> >               .init_regs = imx290_global_init_settings_327,
> >               .init_regs_num = ARRAY_SIZE(imx290_global_init_settings_327),
> > +             .max_analog_gain = 98,
> >               .name = "imx327",
> >       },
> >  };
> >
> >
>
>
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