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