Patch "eeprom: at24: correctly set the size for at24mac402" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

eeprom: at24: correctly set the size for at24mac402

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     eeprom-at24-correctly-set-the-size-for-at24mac402.patch

and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bartosz Golaszewski <[email protected]>
Date: Mon, 27 Nov 2017 22:06:13 +0100
Subject: eeprom: at24: correctly set the size for at24mac402

From: Bartosz Golaszewski <[email protected]>

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.

---
 drivers/misc/eeprom/at24.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

@@ -639,6 +639,16 @@ static int at24_probe(struct i2c_client
 		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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/eeprom-at24-fix-reading-from-24mac402-24mac602.patch queue-4.9/eeprom-at24-check-at24_read-write-arguments.patch queue-4.9/eeprom-at24-correctly-set-the-size-for-at24mac402.patch