drivers/net/ethernet/intel/igb/igb_ptp.c:397: warning: array subscript is below array bounds

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   7c0f6ba682b9c7632072ffbedf8d328c8f3c42ba
commit: d1cbfd771ce8297fa11e89f315392de6056a2181 ptp_clock: Allow for it to be optional
date:   6 weeks ago
config: x86_64-randconfig-s1-12251102 (attached as .config)
compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7
reproduce:
        git checkout d1cbfd771ce8297fa11e89f315392de6056a2181
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/intel/igb/igb_ptp.c: In function 'igb_ptp_feature_enable_i210':
>> drivers/net/ethernet/intel/igb/igb_ptp.c:397: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:400: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:452: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:455: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:458: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:460: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:463: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:465: warning: array subscript is below array bounds
   drivers/net/ethernet/intel/igb/igb_ptp.c:467: warning: array subscript is below array bounds

vim +397 drivers/net/ethernet/intel/igb/igb_ptp.c

720db4ff Richard Cochran 2014-11-21  381  		TS_SDP0_EN, TS_SDP1_EN, TS_SDP2_EN, TS_SDP3_EN,
720db4ff Richard Cochran 2014-11-21  382  	};
b23c0cc5 Alexander Duyck 2015-03-06  383  	struct e1000_hw *hw = &igb->hw;
720db4ff Richard Cochran 2014-11-21  384  	u32 ctrl, ctrl_ext, tssdp = 0;
720db4ff Richard Cochran 2014-11-21  385  
720db4ff Richard Cochran 2014-11-21  386  	ctrl = rd32(E1000_CTRL);
720db4ff Richard Cochran 2014-11-21  387  	ctrl_ext = rd32(E1000_CTRL_EXT);
720db4ff Richard Cochran 2014-11-21  388  	tssdp = rd32(E1000_TSSDP);
720db4ff Richard Cochran 2014-11-21  389  
720db4ff Richard Cochran 2014-11-21  390  	igb_pin_direction(pin, 1, &ctrl, &ctrl_ext);
720db4ff Richard Cochran 2014-11-21  391  
720db4ff Richard Cochran 2014-11-21  392  	/* Make sure this pin is not enabled as an output. */
720db4ff Richard Cochran 2014-11-21  393  	tssdp &= ~ts_sdp_en[pin];
720db4ff Richard Cochran 2014-11-21  394  
720db4ff Richard Cochran 2014-11-21  395  	if (chan == 1) {
720db4ff Richard Cochran 2014-11-21  396  		tssdp &= ~AUX1_SEL_SDP3;
720db4ff Richard Cochran 2014-11-21 @397  		tssdp |= aux1_sel_sdp[pin] | AUX1_TS_SDP_EN;
720db4ff Richard Cochran 2014-11-21  398  	} else {
720db4ff Richard Cochran 2014-11-21  399  		tssdp &= ~AUX0_SEL_SDP3;
720db4ff Richard Cochran 2014-11-21  400  		tssdp |= aux0_sel_sdp[pin] | AUX0_TS_SDP_EN;
720db4ff Richard Cochran 2014-11-21  401  	}
720db4ff Richard Cochran 2014-11-21  402  
720db4ff Richard Cochran 2014-11-21  403  	wr32(E1000_TSSDP, tssdp);
720db4ff Richard Cochran 2014-11-21  404  	wr32(E1000_CTRL, ctrl);
720db4ff Richard Cochran 2014-11-21  405  	wr32(E1000_CTRL_EXT, ctrl_ext);

:::::: The code at line 397 was first introduced by commit
:::::: 720db4ffd0846570c1ddc82e7bb661ab0a676fad igb: enable auxiliary PHC functions for the i210

:::::: TO: Richard Cochran <richardcochran@xxxxxxxxx>
:::::: CC: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>

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