eeprom: at24: correctly set the size for at24mac402

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.

Cc: stable@vger.kernel.org
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>

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index e0b4b36ef01052ea1dd368b33e2170be83bda714..783244b485ccdce70c197026e633370712b5178c 100644 (file)
--- 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)