linux-kernel - Re: [PATCH v2 16/16] media: i2c: ov5647: Add V4L2_CID_LINK

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Message-ID: <5e2lwyzel45ejbb4mch2johetncaj7arpidjst2tjpatseklvn@vlv6hnwzfmwj>
Date: Mon, 1 Dec 2025 16:50:39 +0100
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: Jai Luthra <jai.luthra@...asonboard.com>
Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
	Dave Stevenson <dave.stevenson@...pberrypi.com>, Jacopo Mondi <jacopo@...ndi.org>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, Naushir Patuck <naush@...pberrypi.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
	Kieran Bingham <kieran.bingham@...asonboard.com>, David Plowman <david.plowman@...pberrypi.com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Peter Robinson <pbrobinson@...il.com>, 
	Stefan Wahren <wahrenst@....net>, "Ivan T. Ivanov" <iivanov@...e.de>, 
	Jacopo Mondi <jacopo.mondi@...asonboard.com>
Subject: Re: [PATCH v2 16/16] media: i2c: ov5647: Add V4L2_CID_LINK_FREQUENCY
 control

Hi Jai

On Tue, Nov 18, 2025 at 05:33:09PM +0530, Jai Luthra wrote:
> From: Dave Stevenson <dave.stevenson@...pberrypi.com>
>
> The link frequency can vary between modes, so add it as a
> control.
>
> Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
> ---
>  drivers/media/i2c/ov5647.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> index 71107d74f2900b39233a52b29a229282bd087963..de27e76b487957bfa0a072359f28194425950eaf 100644
> --- a/drivers/media/i2c/ov5647.c
> +++ b/drivers/media/i2c/ov5647.c
> @@ -97,6 +97,13 @@ static const char * const ov5647_supply_names[] = {
>
>  #define OV5647_NUM_SUPPLIES ARRAY_SIZE(ov5647_supply_names)
>
> +#define FREQ_INDEX_FULL		0
> +#define FREQ_INDEX_VGA		1
> +static const s64 ov5647_link_freqs[] = {
> +	[FREQ_INDEX_FULL]	= 218750000,
> +	[FREQ_INDEX_VGA]	= 208333000,
> +};
> +
>  struct regval_list {
>  	u16 addr;
>  	u8 data;
> @@ -106,6 +113,7 @@ struct ov5647_mode {
>  	struct v4l2_mbus_framefmt	format;
>  	struct v4l2_rect		crop;
>  	u64				pixel_rate;
> +	unsigned int			link_freq_index;
>  	int				hts;
>  	int				vts;
>  	const struct regval_list	*reg_list;
> @@ -128,6 +136,7 @@ struct ov5647 {
>  	struct v4l2_ctrl		*exposure;
>  	struct v4l2_ctrl		*hflip;
>  	struct v4l2_ctrl		*vflip;
> +	struct v4l2_ctrl		*link_freq;
>  };
>
>  static inline struct ov5647 *to_sensor(struct v4l2_subdev *sd)
> @@ -376,6 +385,7 @@ static const struct ov5647_mode ov5647_modes[] = {
>  			.height		= 1944
>  		},
>  		.pixel_rate	= 87500000,
> +		.link_freq_index = FREQ_INDEX_FULL,
>  		.hts		= 2844,
>  		.vts		= 0x7b0,
>  		.reg_list	= ov5647_2592x1944_10bpp,
> @@ -397,6 +407,7 @@ static const struct ov5647_mode ov5647_modes[] = {
>  			.height		= 1080,
>  		},
>  		.pixel_rate	= 87500000,
> +		.link_freq_index = FREQ_INDEX_FULL,
>  		.hts		= 2416,
>  		.vts		= 0x450,
>  		.reg_list	= ov5647_1080p30_10bpp,
> @@ -418,6 +429,7 @@ static const struct ov5647_mode ov5647_modes[] = {
>  			.height		= 1944,
>  		},
>  		.pixel_rate	= 87500000,
> +		.link_freq_index = FREQ_INDEX_FULL,
>  		.hts		= 1896,
>  		.vts		= 0x59b,
>  		.reg_list	= ov5647_2x2binned_10bpp,
> @@ -439,6 +451,7 @@ static const struct ov5647_mode ov5647_modes[] = {
>  			.height		= 1920,
>  		},
>  		.pixel_rate	= 55000000,

I now read again v1 13/13 and this mode seems to have a different pixel
rate and a lower link freq ?

> +		.link_freq_index = FREQ_INDEX_VGA,
>  		.hts		= 1852,
>  		.vts		= 0x1f8,
>  		.reg_list	= ov5647_640x480_10bpp,
> @@ -927,6 +940,8 @@ static int ov5647_set_pad_fmt(struct v4l2_subdev *sd,
>  					 sensor->exposure->minimum,
>  					 exposure_max, sensor->exposure->step,
>  					 exposure_def);
> +
> +		__v4l2_ctrl_s_ctrl(sensor->link_freq, mode->link_freq_index);
>  	}
>  	*fmt = mode->format;
>  	/* The code we pass back must reflect the current h/vflips. */
> @@ -1236,7 +1251,7 @@ static int ov5647_init_controls(struct ov5647 *sensor)
>  	int hblank, exposure_max, exposure_def;
>  	struct device *dev = &client->dev;
>
> -	v4l2_ctrl_handler_init(&sensor->ctrls, 13);
> +	v4l2_ctrl_handler_init(&sensor->ctrls, 14);
>
>  	v4l2_ctrl_new_std(&sensor->ctrls, &ov5647_ctrl_ops,
>  			  V4L2_CID_AUTOGAIN, 0, 1, 1, 0);
> @@ -1292,6 +1307,13 @@ static int ov5647_init_controls(struct ov5647 *sensor)
>  	sensor->vflip = v4l2_ctrl_new_std(&sensor->ctrls, &ov5647_ctrl_ops,
>  					  V4L2_CID_VFLIP, 0, 1, 1, 0);
>
> +	sensor->link_freq =
> +		v4l2_ctrl_new_int_menu(&sensor->ctrls, NULL, V4L2_CID_LINK_FREQ,
> +				       ARRAY_SIZE(ov5647_link_freqs) - 1, 0,

The default control value should follow the default mode.
You can use mode->link_req_index to retrieve it

> +				       ov5647_link_freqs);
> +	if (sensor->link_freq)
> +		sensor->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
>  	v4l2_fwnode_device_parse(dev, &props);
>
>  	v4l2_ctrl_new_fwnode_properties(&sensor->ctrls, &ov5647_ctrl_ops,
>
> --
> 2.51.1
>