Re: [PATCH] eeprom: at24: correctly set the size for at24mac402

[Andy Shevchenko]

On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down
> the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6,
> making it impossible to read it all.
>
> Fix it by manually adjusting the value in probe().
>
> This patch contains a temporary fix that is suitable for stable
> branches. Eventually we'll probably remove the call to ilog2() while
> converting the magic values to actual structs.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series")
> Signed-off-by: Bartosz Golaszewski <brgl@xxxxxxxx>
> ---
>  drivers/misc/eeprom/at24.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index e0b4b36ef010..783244b485cc 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -730,6 +730,16 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>                 dev_warn(&client->dev,
>                         "page_size looks suspicious (no power of 2)!\n");
>
> +       /*
> +        * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while
> +        * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4.
> +        *
> +        * Eventually we'll get rid of the magic values altoghether in favor of
> +        * real structs, but for now just manually set the right size.
> +        */
> +       if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4)
> +               chip.byte_len = 6;
> +
>         /* Use I2C operations unless we're stuck with SMBus extensions. */
>         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
>                 if (chip.flags & AT24_FLAG_ADDR16)
> --
> 2.15.0
>



-- 
With Best Regards,
Andy Shevchenko