mlxsw: i2c: Fix chunk size setting in output mailbox buffer

The driver reads commands output from the output mailbox. If the size
of the output mailbox is not a multiple of the transaction /
block size, then the driver will not issue enough read transactions
to read the entire output, which can result in driver initialization
errors.

Fix by determining the number of transactions using DIV_ROUND_UP().

Fixes: 3029a693beda ("mlxsw: i2c: Allow flexible setting of I2C transactions size")
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlxsw/i2c.c b/drivers/net/ethernet/mellanox/mlxsw/i2c.c
index 41298835a11e1673221fdda27dab5fb650ce6cd7..47af7ef7e4eeee4a90d8c5f84b1ca8ba0cfb4fea 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlxsw/i2c.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/i2c.c
@@ -444,7 +444,7 @@ mlxsw_i2c_cmd(struct device *dev, u16 opcode, u32 in_mod, size_t in_mbox_size,
        } else {
                /* No input mailbox is case of initialization query command. */
                reg_size = MLXSW_I2C_MAX_DATA_SIZE;
-               num = reg_size / mlxsw_i2c->block_size;
+               num = DIV_ROUND_UP(reg_size, mlxsw_i2c->block_size);
 
                if (mutex_lock_interruptible(&mlxsw_i2c->cmd.lock) < 0) {
                        dev_err(&client->dev, "Could not acquire lock");