eeprom: at24: correctly set the size for at24mac402

commit 5478e478eee3b096b8d998d4ed445da30da2dfbc upstream.

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.

Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index bfd1a6f4ebf6972dfda815d0da6f43350322ee43..e0d018e8bb8e14dd50da5870bf4f74859d56ec1a 100644 (file)
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -632,6 +632,16 @@ 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)