Re: [PATCH v12] media: Add t4ka3 camera sensor driver

[Sakari Ailus]

Hi Kate,

Thanks for the update.

On Mon, Mar 23, 2026 at 03:16:47PM +0800, Kate Hsuan wrote:

...

> +static int t4ka3_set_pad_format(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *sd_state,
> +				struct v4l2_subdev_format *format)
> +{
> +	struct t4ka3_data *sensor = to_t4ka3_sensor(sd);
> +	struct v4l2_mbus_framefmt *try_fmt;
> +	struct v4l2_mbus_framefmt *fmt = &format->format;
> +	struct v4l2_rect *crop =
> +		v4l2_subdev_state_get_crop(sd_state, format->pad);
> +	unsigned int width, height;
> +	int min, max, def, ret = 0;
> +
> +	/* Limit set_fmt max size to crop width / height */
> +	width = clamp_val(ALIGN(format->format.width, 2),
> +			  T4KA3_MIN_CROP_WIDTH, crop->width);
> +	height = clamp_val(ALIGN(format->format.height, 2),
> +			   T4KA3_MIN_CROP_HEIGHT, crop->height);
> +	t4ka3_fill_format(sensor, &format->format, width, height);
> +
> +	if (format->which == V4L2_SUBDEV_FORMAT_TRY) {

You can move this check after the format assignment below and just return
0.

> +		try_fmt = v4l2_subdev_state_get_format(sd_state, 0);
> +		*try_fmt = format->format;
> +		return 0;
> +	}
> +
> +	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE && sensor->streaming)
> +		return -EBUSY;
> +
> +	*v4l2_subdev_state_get_format(sd_state, 0) = format->format;
> +
> +	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
> +		return 0;
> +
> +	t4ka3_calc_mode(sensor, fmt, crop);
> +
> +	/* vblank range is height dependent adjust and reset to default */
> +	t4ka3_get_vblank_limits(sensor, sd_state, &min, &max, &def);
> +	ret = __v4l2_ctrl_modify_range(sensor->ctrls.vblank, min, max, 1, def);
> +	if (ret)
> +		return ret;
> +
> +	ret = __v4l2_ctrl_s_ctrl(sensor->ctrls.vblank, def);
> +	if (ret)
> +		return ret;
> +
> +	def = T4KA3_PIXELS_PER_LINE - fmt->width;
> +	ret = __v4l2_ctrl_modify_range(sensor->ctrls.hblank, def, def, 1, def);
> +	if (ret)
> +		return ret;
> +
> +	return  __v4l2_ctrl_s_ctrl(sensor->ctrls.hblank, def);
> +}

...

> +static int t4ka3_set_mode(struct t4ka3_data *sensor,
> +			  struct v4l2_subdev_state *state)
> +{
> +	struct v4l2_mbus_framefmt *fmt = v4l2_subdev_state_get_format(state, 0);
> +	int ret = 0;
> +
> +	cci_write(sensor->regmap, T4KA3_REG_HORZ_OUTPUT_SIZE, fmt->width, &ret);
> +	/* Write mode-height - 2 otherwise things don't work, hw-bug ? */
> +	cci_write(sensor->regmap, T4KA3_REG_VERT_OUTPUT_SIZE,
> +		  fmt->height - 2, &ret);
> +	/*
> +	 * Note overwritten by __v4l2_ctrl_handler_setup() based on
> +	 * vblank ctrl
> +	 */
> +	cci_write(sensor->regmap, T4KA3_REG_FRAME_LENGTH_LINES,
> +		  T4KA3_LINES_PER_FRAME_30FPS, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_PIXELS_PER_LINE,
> +		  T4KA3_PIXELS_PER_LINE, &ret);

These two appear to be redundant as they're written though
__v4l2_ctrl_handler_setup() below.

> +	/* Always use the full sensor, using window to crop */
> +	cci_write(sensor->regmap, T4KA3_REG_HORZ_START, 0, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_VERT_START, 0, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_HORZ_END,
> +		  T4KA3_NATIVE_WIDTH - 1, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_VERT_END,
> +		  T4KA3_NATIVE_HEIGHT - 1, &ret);
> +	/* Set window */
> +	cci_write(sensor->regmap, T4KA3_REG_WIN_START_X,
> +		  sensor->mode.win_x, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_WIN_START_Y,
> +		  sensor->mode.win_y, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_WIN_WIDTH, fmt->width, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_WIN_HEIGHT, fmt->height, &ret);
> +	/* Write 1 to unknown register 0x0900 */
> +	cci_write(sensor->regmap, T4KA3_REG_0900, 1, &ret);
> +	cci_write(sensor->regmap, T4KA3_REG_BINNING,
> +		  T4KA3_BINNING_VAL(sensor->mode.binning), &ret);
> +
> +	return ret;
> +}

...

> +static int t4ka3_check_hwcfg(struct t4ka3_data *sensor)
> +{
> +	struct fwnode_handle *fwnode = dev_fwnode(sensor->dev);
> +	struct v4l2_fwnode_endpoint bus_cfg = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY,
> +	};
> +	struct fwnode_handle *endpoint;
> +	unsigned long link_freq_bitmap;
> +	int ret;
> +
> +	endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
> +
> +	ret = v4l2_fwnode_endpoint_alloc_parse(endpoint, &bus_cfg);
> +	fwnode_handle_put(endpoint);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_link_freq_to_bitmap(sensor->dev, bus_cfg.link_frequencies,
> +				       bus_cfg.nr_of_link_frequencies,
> +				       link_freq_menu_items,
> +				       ARRAY_SIZE(link_freq_menu_items),
> +				       &link_freq_bitmap);
> +
> +	if (ret == -ENOENT)
> +		goto out_free_bus_cfg;
> +
> +	if (ret == -ENODATA)
> +		goto out_free_bus_cfg;

Please check for any non-zero return value instead.

> +
> +	sensor->link_freq_index = ffs(link_freq_bitmap) - 1;
> +
> +	/* 4 MIPI lanes */
> +	if (bus_cfg.bus.mipi_csi2.num_data_lanes != 4) {
> +		ret = dev_err_probe(sensor->dev, -EINVAL,
> +				    "number of CSI2 data lanes %u is not supported\n",
> +				    bus_cfg.bus.mipi_csi2.num_data_lanes);
> +		goto out_free_bus_cfg;
> +	}
> +
> +	sensor->mipi_lanes = bus_cfg.bus.mipi_csi2.num_data_lanes;
> +
> +out_free_bus_cfg:
> +	v4l2_fwnode_endpoint_free(&bus_cfg);
> +
> +	return ret;
> +}

I'll take this one now but please submit a patch on top to address the
above.

-- 
Kind regards,

Sakari Ailus