linux-kernel - Re: [PATCH v7 2/2] media: i2c: add Himax HM1246 image sensor driver

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Message-ID: <aWVFE-Y5HRi_XZRE@smile.fi.intel.com>
Date: Mon, 12 Jan 2026 21:01:39 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Matthias Fend <matthias.fend@...end.at>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Hans Verkuil <hverkuil@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Hans de Goede <hansg@...nel.org>,
	Ricardo Ribalda <ribalda@...omium.org>,
	André Apitzsch <git@...tzsch.eu>,
	Tarang Raval <tarang.raval@...iconsignals.io>,
	Benjamin Mugnier <benjamin.mugnier@...s.st.com>,
	Sylvain Petinot <sylvain.petinot@...s.st.com>,
	Dongcheng Yan <dongcheng.yan@...el.com>,
	Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Jingjing Xiong <jingjing.xiong@...el.com>,
	Heimir Thor Sverrisson <heimir.sverrisson@...il.com>,
	Mehdi Djait <mehdi.djait@...ux.intel.com>,
	Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Hardevsinh Palaniya <hardevsinh.palaniya@...iconsignals.io>,
	Svyatoslav Ryhel <clamor95@...il.com>, linux-media@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Hao Yao <hao.yao@...el.com>,
	Himanshu Bhavani <himanshu.bhavani@...iconsignals.io>,
	bsp-development.geo@...ca-geosystems.com
Subject: Re: [PATCH v7 2/2] media: i2c: add Himax HM1246 image sensor driver

On Mon, Jan 12, 2026 at 03:49:33PM +0100, Matthias Fend wrote:
> Add a V4L2 sub-device driver for Himax HM1246 image sensor.
> 
> The Himax HM1246-AWD is a 1/3.7-Inch CMOS image sensor SoC with an active
> array size of 1296 x 976. It is programmable through an I2C interface and
> connected via parallel bus.
> 
> The sensor has an internal ISP with a complete image processing pipeline
> including control loops. However, this driver uses the sensor in raw mode
> and the entire ISP is bypassed.

...

> +struct hm1246_mode {
> +	u32 codes[4];
> +	u32 clocks_per_pixel;

> +	u32 top;
> +	u32 left;
> +	u32 width;
> +	u32 height;

Why not use struct v4l2_rect?

> +	u32 hts;
> +	u32 vts_min;
> +	const struct hm1246_reg_list reg_list;
> +};

...

> +static int hm1246_set_format(struct v4l2_subdev *sd,
> +			     struct v4l2_subdev_state *state,
> +			     struct v4l2_subdev_format *fmt)
> +{
> +	struct hm1246 *hm1246 = to_hm1246(sd);
> +	struct v4l2_mbus_framefmt *mbus_fmt;
> +	struct v4l2_rect *crop;
> +	const struct hm1246_mode *mode;
> +
> +	mode = hm1246_find_mode_by_mbus_code(hm1246, fmt->format.code);
> +	if (IS_ERR(mode))
> +		mode = &hm1246_modes[0];
> +
> +	crop = v4l2_subdev_state_get_crop(state, 0);

> +	crop->top = mode->top;
> +	crop->left = mode->left;
> +	crop->width = mode->width;
> +	crop->height = mode->height;

With the above done this becomes a one-liner:

	*crop = mode.<rect>; // <rect> is whatever name for the embedded field

> +	hm1246_update_pad_format(hm1246, mode, &fmt->format);
> +	mbus_fmt = v4l2_subdev_state_get_format(state, 0);
> +	*mbus_fmt = fmt->format;
> +
> +	return 0;
> +}

...

> +static int hm1246_get_selection(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *state,
> +				struct v4l2_subdev_selection *sel)
> +{
> +	const struct v4l2_mbus_framefmt *format;
> +	const struct hm1246_mode *mode;
> +
> +	format = v4l2_subdev_state_get_format(state, 0);
> +	mode = v4l2_find_nearest_size(hm1246_modes, ARRAY_SIZE(hm1246_modes),
> +				      width, height, format->width,
> +				      format->height);
> +
> +	switch (sel->target) {
> +	case V4L2_SEL_TGT_CROP:
> +		sel->r = *v4l2_subdev_state_get_crop(state, 0);
> +		return 0;
> +
> +	case V4L2_SEL_TGT_NATIVE_SIZE:
> +		sel->r.top = 0;
> +		sel->r.left = 0;
> +		sel->r.width = HM1246_NATIVE_WIDTH;
> +		sel->r.height = HM1246_NATIVE_HEIGHT;
> +		return 0;
> +
> +	case V4L2_SEL_TGT_CROP_DEFAULT:
> +	case V4L2_SEL_TGT_CROP_BOUNDS:

> +		sel->r.top = mode->top;
> +		sel->r.left = mode->left;
> +		sel->r.width = mode->width;
> +		sel->r.height = mode->height;

Seems in the same way here.

> +		return 0;
> +	}

> +	return -EINVAL;

Why not making it a default case?

> +}

...

> +	hm1246->reset_gpio =
> +		devm_gpiod_get_optional(hm1246->dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(hm1246->reset_gpio))
> +		return dev_err_probe(hm1246->dev, PTR_ERR(hm1246->reset_gpio),
> +				     "failed to get reset GPIO\n");

Can it be GPIO reset driver used instead? (Note, it's made agnostic now.)

-- 
With Best Regards,
Andy Shevchenko