Re: [PATCH 2/2] media: ov9282: enable single-read I2C transactions

[Dave Stevenson]

Hi Richard

On Tue, 21 Jul 2026 at 14:25, Richard Leitner <richard.leitner@xxxxxxxxx> wrote:
>
> Some OV9282 camera modules, such as those from Vision Components, fail
> multi-byte register reads with the default CCI I2C regmap access pattern
> and only work when single-register read transactions are used. This
> results in the driver being unable to probe due to a chip id mismatch.

Those damn stupid Vision Components modules with the MCU that prevents
you reading registers.

I seem to recall Laurent had a plan for how to handle those without
having to patch all the drivers, however I can't find that thread
quickly.

> As the driver has no reliable way to identify affected modules enable
> use_single_read for OV9282 unconditionally when creating the CCI regmap.
>
> Tested on an i.M8MP system with OV9282 modules from Vision Components.
>
> Signed-off-by: Richard Leitner <richard.leitner@xxxxxxxxx>

As regmap does provide a simple way to request this behaviour, and the
only read is the ID register from ov9282_detect, I'll give it an

Acked-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>

but it's not an ideal situation. Others can debate the alternative
approaches for handling VC modules.

  Dave

> ---
>  drivers/media/i2c/ov9282.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> index 5b6f897a74fcd..8267a0a9c6f2d 100644
> --- a/drivers/media/i2c/ov9282.c
> +++ b/drivers/media/i2c/ov9282.c
> @@ -1283,6 +1283,11 @@ static int ov9282_probe(struct i2c_client *client)
>         struct ov9282 *ov9282;
>         int ret;
>
> +       const struct cci_regmap_config config = {
> +               .reg_addr_bits = 16,
> +               .use_single_read = true,
> +       };
> +
>         ov9282 = devm_kzalloc(&client->dev, sizeof(*ov9282), GFP_KERNEL);
>         if (!ov9282)
>                 return -ENOMEM;
> @@ -1301,7 +1306,7 @@ static int ov9282_probe(struct i2c_client *client)
>                 return ret;
>         }
>
> -       ov9282->regmap = devm_cci_regmap_init_i2c(client, 16);
> +       ov9282->regmap = devm_cci_regmap_init_i2c_cfg(client, &config);
>         if (IS_ERR(ov9282->regmap))
>                 return dev_err_probe(ov9282->dev, PTR_ERR(ov9282->regmap),
>                                      "Failed to init CCI\n");
>
> --
> 2.53.0
>
>