Re: [PATCH] i2c: Add i2c_get_match_data()

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Biju,

On Mon, May 22, 2023 at 12:42 PM Biju Das <biju.das.jz@bp.renesas.com> wrote:
> Add i2c_get_match_data() similar to of_device_get_match_data(),
> so that we can optimize the driver code that uses both I2C and
> DT-based matching.
>
> Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -99,8 +99,8 @@ const char *i2c_freq_mode_string(u32 bus_freq_hz)
>  }
>  EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
>
> -const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
> -                                               const struct i2c_client *client)
> +static const struct i2c_device_id *i2c_match_device_id(const struct i2c_device_id *id,
> +                                                      const struct i2c_client *client)
>  {
>         if (!(id && client))
>                 return NULL;
> @@ -110,10 +110,30 @@ const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
>                         return id;
>                 id++;
>         }
> +
>         return NULL;
>  }
> +
> +const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
> +                                        const struct i2c_client *client)
> +{
> +       return i2c_match_device_id(id, client);
> +}
>  EXPORT_SYMBOL_GPL(i2c_match_id);

Is there any reason why you're adding a new intermediate?

>
> +const void *i2c_get_match_data(const struct i2c_device_id *id,
> +                              const struct i2c_client *client)

I think this should take the id table from the i2c_driver, as pointed to
by client->dev.driver, instead of from an explicitly passed parameter.

> +{
> +       const struct i2c_device_id *match;
> +
> +       match = i2c_match_device_id(id, client);
> +       if (!match)
> +               return NULL;
> +
> +       return (const void *)match->driver_data;

One can discuss about the returned type: personally, I won't mind
"const void *" for consistency with other subsystems (e.g. DT), but
as i2c_device_id.driver_data has type "kernel_ulong_t", other people
might prefer the latter.

> +}
> +EXPORT_SYMBOL(i2c_get_match_data);

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds