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Subject[PATCH] eeprom: at24: correctly set the size for at24mac402
Date
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>
---
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
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