net: sfp: initialize sfp->i2c_block_size at sfp allocation

stable inclusion
from stable-v5.10.178
commit cf22c98bcbf8fc0660a1f09fe324fd4f45ae179a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8D927

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cf22c98bcbf8fc0660a1f09fe324fd4f45ae179a



--------------------------------

commit 813c2dd7 upstream.

sfp->i2c_block_size is initialized at SFP module insertion in
sfp_sm_mod_probe(). Because of that, if SFP module was never inserted
since boot, sfp_read() call will lead to zero-length I2C read attempt,
and not all I2C controllers are happy with zero-length reads.

One way to issue sfp_read() on empty SFP cage is to execute ethtool -m.
If SFP module was never plugged since boot, there will be a zero-length
I2C read attempt.

  # ethtool -m xge0
  i2c i2c-3: adapter quirk: no zero length (addr 0x0050, size 0, read)
  Cannot get Module EEPROM data: Operation not supported

If SFP module was plugged then removed at least once,
sfp->i2c_block_size will be initialized and ethtool -m will fail with
different exit code and without I2C error

  # ethtool -m xge0
  Cannot get Module EEPROM data: Remote I/O error

Fix this by initializing sfp->i2_block_size at struct sfp allocation
stage so no wild sfp_read() could issue zero-length I2C read.

Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Fixes: 0d035bed ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround")
Cc: stable@vger.kernel.org
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>