netdev - [net-next:master 664/670] drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c:1421:7-9: WARNING: possible condition with no effect (if == else)

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Date:   Sun, 13 Nov 2016 19:12:42 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     "Lendacky, Thomas" <Thomas.Lendacky@....com>
cc:     netdev@...r.kernel.org, kbuild-all@...org
Subject: [net-next:master 664/670] drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c:1421:7-9:
 WARNING: possible condition with no effect (if == else)

It looks like the code on lines 1422 and 1424 is the same, so either the
test may be unnecessary, or one of the branches is wrong.

Coccinelle is also comparing about a comparison on an unsigned value in
line 1900, but the code for that is not listed in the report below.

julia

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head:   f7ad3d4b83e694347cddc96d956143068bef32c9
commit: abf0a1c2b26ad964d19b143ce46735e1b0667f29 [664/670] amd-xgbe: Add support for SFP+ modules
:::::: branch date: 16 minutes ago
:::::: commit date: 12 hours ago

>> drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c:1421:7-9: WARNING: possible condition with no effect (if == else)
--
>> drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c:1900:6-9: WARNING: Unsigned expression compared with zero: ret < 0

git remote add net-next https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
git remote update net-next
git checkout abf0a1c2b26ad964d19b143ce46735e1b0667f29
vim +1421 drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c

abf0a1c2 Lendacky, Thomas 2016-11-10  1405  {
abf0a1c2 Lendacky, Thomas 2016-11-10  1406  	struct xgbe_phy_data *phy_data = pdata->phy_data;
abf0a1c2 Lendacky, Thomas 2016-11-10  1407  	unsigned int s0;
abf0a1c2 Lendacky, Thomas 2016-11-10  1408
abf0a1c2 Lendacky, Thomas 2016-11-10  1409  	xgbe_phy_start_ratechange(pdata);
abf0a1c2 Lendacky, Thomas 2016-11-10  1410
abf0a1c2 Lendacky, Thomas 2016-11-10  1411  	/* 10G/SFI */
abf0a1c2 Lendacky, Thomas 2016-11-10  1412  	s0 = 0;
abf0a1c2 Lendacky, Thomas 2016-11-10  1413  	XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, COMMAND, 3);
abf0a1c2 Lendacky, Thomas 2016-11-10  1414  	if (phy_data->sfp_cable != XGBE_SFP_CABLE_PASSIVE) {
abf0a1c2 Lendacky, Thomas 2016-11-10  1415  		XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, SUB_COMMAND, 0);
abf0a1c2 Lendacky, Thomas 2016-11-10  1416  	} else {
abf0a1c2 Lendacky, Thomas 2016-11-10  1417  		if (phy_data->sfp_cable_len <= 1)
abf0a1c2 Lendacky, Thomas 2016-11-10  1418  			XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, SUB_COMMAND, 1);
abf0a1c2 Lendacky, Thomas 2016-11-10  1419  		else if (phy_data->sfp_cable_len <= 3)
abf0a1c2 Lendacky, Thomas 2016-11-10  1420  			XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, SUB_COMMAND, 2);
abf0a1c2 Lendacky, Thomas 2016-11-10 @1421  		else if (phy_data->sfp_cable_len <= 5)
abf0a1c2 Lendacky, Thomas 2016-11-10  1422  			XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, SUB_COMMAND, 3);
abf0a1c2 Lendacky, Thomas 2016-11-10  1423  		else
abf0a1c2 Lendacky, Thomas 2016-11-10  1424  			XP_SET_BITS(s0, XP_DRIVER_SCRATCH_0, SUB_COMMAND, 3);
abf0a1c2 Lendacky, Thomas 2016-11-10  1425  	}
abf0a1c2 Lendacky, Thomas 2016-11-10  1426
abf0a1c2 Lendacky, Thomas 2016-11-10  1427  	/* Call FW to make the change */
abf0a1c2 Lendacky, Thomas 2016-11-10  1428  	XP_IOWRITE(pdata, XP_DRIVER_SCRATCH_0, s0);
abf0a1c2 Lendacky, Thomas 2016-11-10  1429  	XP_IOWRITE(pdata, XP_DRIVER_SCRATCH_1, 0);

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