linux-kernel - [RFC PATCH 1/2] i2c: mlxcpld: check correct size of maximum RECV

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Date:   Sun, 28 Jun 2020 13:52:44 +0200
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     linux-i2c@...r.kernel.org
Cc:     linux-renesas-soc@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Vadim Pasternak <vadimp@...lanox.com>,
        Michael Shych <michaelsh@...lanox.com>,
        Wolfram Sang <wsa@...nel.org>, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 1/2] i2c: mlxcpld: check correct size of maximum RECV_LEN packet

I2C_SMBUS_BLOCK_MAX defines already the maximum number as defined in the
SMBus 2.0 specs. I don't see a reason to add 1 here. Also, fix the errno
to what is suggested for this error.

Fixes: c9bfdc7c16cb ("i2c: mlxcpld: Add support for smbus block read transaction")
Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
---

Only build tested, I don't have the HW. Please let me know if I
overlooked something, but to the best of my knowledge, this +1 is wrong.

 drivers/i2c/busses/i2c-mlxcpld.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mlxcpld.c b/drivers/i2c/busses/i2c-mlxcpld.c
index 2fd717d8dd30..71d7bae2cbca 100644
--- a/drivers/i2c/busses/i2c-mlxcpld.c
+++ b/drivers/i2c/busses/i2c-mlxcpld.c
@@ -337,9 +337,9 @@ static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv *priv)
 		if (priv->smbus_block && (val & MLXCPLD_I2C_SMBUS_BLK_BIT)) {
 			mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_NUM_DAT_REG,
 					      &datalen, 1);
-			if (unlikely(datalen > (I2C_SMBUS_BLOCK_MAX + 1))) {
+			if (unlikely(datalen > I2C_SMBUS_BLOCK_MAX)) {
 				dev_err(priv->dev, "Incorrect smbus block read message len\n");
-				return -E2BIG;
+				return -EPROTO;
 			}
 		} else {
 			datalen = priv->xfer.data_len;
-- 
2.20.1