Re: [PATCH] media: i2c: imx334: add new link frequency configuration

[Dave Stevenson]

Hi Shravan

On Tue, 19 May 2026 at 12:17, shravan kumar
<shravan.chippa@xxxxxxxxxxxxx> wrote:
>
> From: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx>
>
> Add support for a new 222 MHz link frequency configuration to the
> IMX334 driver and dynamically generate the supported modes array
> based on the link frequencies specified in the DTS. When multiple
> link frequencies support the same resolution, the driver selects
> the first matching entry; therefore, the link frequency must be
> explicitly defined in the DTS to avoid resolution conflicts.
> The link frequency is a read‑only parameter and is automatically
> set based on the selected resolution and DTS configuration.

Where is the sensor setup to configure this 222MHz link frequency?

I have a datasheet that lists support for 1782, 1188, and 891Mbit/s,
which equates to 891, 594, and 445.5MHz link frequencies. There is no
mention of supporting 444Mbit/s or 222MHz.
The driver switches from the default 445.5MHz to 891MHz by changing
SYS_MODE from 0x02 to 0x00 (it's an 8bit register, so I don't know why
it's trying to write 0x0100).

As far as I can tell, this patch just changes the advertised link
frequency, but the sensor will produce exactly the same 445.5MHz
output. Can you tell me what I've missed?

Thanks
  Dave

> Signed-off-by: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx>
> ---
>  drivers/media/i2c/imx334.c | 112 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 106 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/i2c/imx334.c b/drivers/media/i2c/imx334.c
> index 9654f9268056..336de9cd8ff2 100644
> --- a/drivers/media/i2c/imx334.c
> +++ b/drivers/media/i2c/imx334.c
> @@ -109,6 +109,7 @@
>  /* CSI2 HW configuration */
>  #define IMX334_LINK_FREQ_891M          891000000
>  #define IMX334_LINK_FREQ_445M          445500000
> +#define IMX334_LINK_FREQ_222M          222500000
>  #define IMX334_NUM_DATA_LANES          4
>
>  #define IMX334_REG_MIN                 0x00
> @@ -209,6 +210,8 @@ struct imx334 {
>         };
>         u32 vblank;
>         const struct imx334_mode *cur_mode;
> +       const struct imx334_mode *new_supported_modes;
> +       int new_modes_size;
>         unsigned long link_freq_bitmap;
>         u32 cur_code;
>  };
> @@ -216,6 +219,7 @@ struct imx334 {
>  static const s64 link_freq[] = {
>         IMX334_LINK_FREQ_891M,
>         IMX334_LINK_FREQ_445M,
> +       IMX334_LINK_FREQ_222M,
>  };
>
>  /* Sensor common mode registers values */
> @@ -486,6 +490,45 @@ static const struct imx334_mode supported_modes[] = {
>                         .num_of_regs = ARRAY_SIZE(mode_640x480_regs),
>                         .regs = mode_640x480_regs,
>                 },
> +       }, {
> +               .width = 1920,
> +               .height = 1080,
> +               .hblank = 2480,
> +               .vblank = 1170,
> +               .vblank_min = 45,
> +               .vblank_max = 132840,
> +               .pclk = 297000000,
> +               .link_freq_idx = 2,
> +               .reg_list = {
> +                       .num_of_regs = ARRAY_SIZE(mode_1920x1080_regs),
> +                       .regs = mode_1920x1080_regs,
> +               },
> +       }, {
> +               .width = 1280,
> +               .height = 720,
> +               .hblank = 2480,
> +               .vblank = 1170,
> +               .vblank_min = 45,
> +               .vblank_max = 132840,
> +               .pclk = 297000000,
> +               .link_freq_idx = 2,
> +               .reg_list = {
> +                       .num_of_regs = ARRAY_SIZE(mode_1280x720_regs),
> +                       .regs = mode_1280x720_regs,
> +               },
> +       }, {
> +               .width = 640,
> +               .height = 480,
> +               .hblank = 2480,
> +               .vblank = 1170,
> +               .vblank_min = 45,
> +               .vblank_max = 132840,
> +               .pclk = 297000000,
> +               .link_freq_idx = 2,
> +               .reg_list = {
> +                       .num_of_regs = ARRAY_SIZE(mode_640x480_regs),
> +                       .regs = mode_640x480_regs,
> +               },
>         },
>  };
>
> @@ -713,7 +756,7 @@ static int imx334_enum_frame_size(struct v4l2_subdev *sd,
>         struct imx334 *imx334 = to_imx334(sd);
>         u32 code;
>
> -       if (fsize->index >= ARRAY_SIZE(supported_modes))
> +       if (fsize->index >= imx334->new_modes_size)
>                 return -EINVAL;
>
>         code = imx334_get_format_code(imx334, fsize->code);
> @@ -721,9 +764,9 @@ static int imx334_enum_frame_size(struct v4l2_subdev *sd,
>         if (fsize->code != code)
>                 return -EINVAL;
>
> -       fsize->min_width = supported_modes[fsize->index].width;
> +       fsize->min_width = imx334->new_supported_modes[fsize->index].width;
>         fsize->max_width = fsize->min_width;
> -       fsize->min_height = supported_modes[fsize->index].height;
> +       fsize->min_height = imx334->new_supported_modes[fsize->index].height;
>         fsize->max_height = fsize->min_height;
>
>         return 0;
> @@ -792,8 +835,8 @@ static int imx334_set_pad_format(struct v4l2_subdev *sd,
>         const struct imx334_mode *mode;
>         int ret = 0;
>
> -       mode = v4l2_find_nearest_size(supported_modes,
> -                                     ARRAY_SIZE(supported_modes),
> +       mode = v4l2_find_nearest_size(imx334->new_supported_modes,
> +                                     imx334->new_modes_size,
>                                       width, height,
>                                       fmt->format.width, fmt->format.height);
>
> @@ -914,6 +957,9 @@ static int imx334_enable_streams(struct v4l2_subdev *sd,
>                 goto err_rpm_put;
>         }
>
> +       if (link_freq[imx334->cur_mode->link_freq_idx] == IMX334_LINK_FREQ_222M)
> +               cci_write(imx334->cci, IMX334_REG_INCKSEL2, 0x0a, NULL);
> +
>         /* Start streaming */
>         ret = cci_write(imx334->cci, IMX334_REG_MODE_SELECT,
>                         IMX334_MODE_STREAMING, NULL);
> @@ -979,6 +1025,55 @@ static int imx334_detect(struct imx334 *imx334)
>         return 0;
>  }
>
> +/**
> + * imx334_update_supported_mode_array() - Search for the supported
> + *                                        modes add them in the new list
> + * @imx334: pointer to imx334 device
> + *
> + * Return: 0 if successful, error code otherwise.
> + */
> +static int imx334_update_supported_mode_array(struct imx334 *imx334)
> +{
> +       int i, j, size = 0;
> +       struct imx334_mode *temp_ptr;
> +
> +       for (i = 0; i < ARRAY_SIZE(link_freq); i++) {
> +               if (imx334->link_freq_bitmap & (1 << i)) {
> +                       for (j = 0; j < ARRAY_SIZE(supported_modes); j++) {
> +                               if (supported_modes[j].link_freq_idx == i)
> +                                       size++;
> +                       }
> +               }
> +       }
> +
> +       if (!size)
> +               return -EINVAL;
> +
> +       imx334->new_modes_size = size;
> +
> +       size = 0;
> +
> +       temp_ptr = devm_kmalloc(imx334->dev, imx334->new_modes_size * sizeof(struct imx334_mode),
> +                               GFP_KERNEL);
> +       if (!temp_ptr)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < ARRAY_SIZE(link_freq); i++) {
> +               if (imx334->link_freq_bitmap & (1 << i)) {
> +                       for (j = 0; j < ARRAY_SIZE(supported_modes); j++) {
> +                               if (supported_modes[j].link_freq_idx == i) {
> +                                       temp_ptr[size] = supported_modes[j];
> +                                       size++;
> +                               }
> +                       }
> +               }
> +       }
> +
> +       imx334->new_supported_modes = temp_ptr;
> +
> +       return 0;
> +}
> +
>  /**
>   * imx334_parse_hw_config() - Parse HW configuration and check if supported
>   * @imx334: pointer to imx334 device
> @@ -1038,6 +1133,11 @@ static int imx334_parse_hw_config(struct imx334 *imx334)
>                                        link_freq, ARRAY_SIZE(link_freq),
>                                        &imx334->link_freq_bitmap);
>
> +       if (ret)
> +               goto done_endpoint_free;
> +
> +       ret = imx334_update_supported_mode_array(imx334);
> +
>  done_endpoint_free:
>         v4l2_fwnode_endpoint_free(&bus_cfg);
>
> @@ -1251,7 +1351,7 @@ static int imx334_probe(struct i2c_client *client)
>         }
>
>         /* Set default mode to max resolution */
> -       imx334->cur_mode = &supported_modes[__ffs(imx334->link_freq_bitmap)];
> +       imx334->cur_mode = &imx334->new_supported_modes[__ffs(imx334->link_freq_bitmap)];
>         imx334->cur_code = imx334_mbus_codes[0];
>         imx334->vblank = imx334->cur_mode->vblank;
>
> --
> 2.34.1
>
>