linux-kernel - Re: [PATCH 11/12] i2c: qup: reorganization of driver code to remove polling for qup v1

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Date:   Tue, 6 Feb 2018 07:03:38 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Abhishek Sahu <absahu@...eaurora.org>
Cc:     kbuild-all@...org, Andy Gross <andy.gross@...aro.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        David Brown <david.brown@...aro.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Abhishek Sahu <absahu@...eaurora.org>
Subject: Re: [PATCH 11/12] i2c: qup: reorganization of driver code to remove
 polling for qup v1

Hi Abhishek,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on wsa/i2c/for-next]
[also build test WARNING on v4.15 next-20180205]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Abhishek-Sahu/Major-code-reorganization-to-make-all-i2c-transfers-working/20180206-035527
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: arm64-defconfig (attached as .config)
compiler: aarch64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/i2c/busses/i2c-qup.c: In function 'qup_i2c_read_rx_fifo_v1':
>> drivers/i2c/busses/i2c-qup.c:1139:12: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
      if ((idx & 1) == 0) {
          ~~~~~^~~~

vim +/idx +1139 drivers/i2c/busses/i2c-qup.c

191424bb Sricharan R     2016-01-19  1130  
3a487e36 Abhishek Sahu   2018-02-03  1131  static void qup_i2c_read_rx_fifo_v1(struct qup_i2c_dev *qup)
10c5a842 Bjorn Andersson 2014-03-13  1132  {
3a487e36 Abhishek Sahu   2018-02-03  1133  	struct qup_i2c_block *blk = &qup->blk;
3a487e36 Abhishek Sahu   2018-02-03  1134  	struct i2c_msg *msg = qup->msg;
10c5a842 Bjorn Andersson 2014-03-13  1135  	u32 val = 0;
10c5a842 Bjorn Andersson 2014-03-13  1136  	int idx;
10c5a842 Bjorn Andersson 2014-03-13  1137  
3a487e36 Abhishek Sahu   2018-02-03  1138  	while (blk->fifo_available && qup->pos < msg->len) {
10c5a842 Bjorn Andersson 2014-03-13 @1139  		if ((idx & 1) == 0) {
10c5a842 Bjorn Andersson 2014-03-13  1140  			/* Reading 2 words at time */
10c5a842 Bjorn Andersson 2014-03-13  1141  			val = readl(qup->base + QUP_IN_FIFO_BASE);
10c5a842 Bjorn Andersson 2014-03-13  1142  			msg->buf[qup->pos++] = val & 0xFF;
10c5a842 Bjorn Andersson 2014-03-13  1143  		} else {
10c5a842 Bjorn Andersson 2014-03-13  1144  			msg->buf[qup->pos++] = val >> QUP_MSW_SHIFT;
10c5a842 Bjorn Andersson 2014-03-13  1145  		}
3a487e36 Abhishek Sahu   2018-02-03  1146  		idx++;
3a487e36 Abhishek Sahu   2018-02-03  1147  		blk->fifo_available--;
10c5a842 Bjorn Andersson 2014-03-13  1148  	}
c4f0c5fb Sricharan R     2016-01-19  1149  
3a487e36 Abhishek Sahu   2018-02-03  1150  	if (qup->pos == msg->len)
3a487e36 Abhishek Sahu   2018-02-03  1151  		qup->cur_blk_events |= QUP_BLK_EVENT_RX_DATA_DONE;
10c5a842 Bjorn Andersson 2014-03-13  1152  }
10c5a842 Bjorn Andersson 2014-03-13  1153  

:::::: The code at line 1139 was first introduced by commit
:::::: 10c5a8425968f8a43b7039ce6261367fc992289f i2c: qup: New bus driver for the Qualcomm QUP I2C controller

:::::: TO: Bjorn Andersson <bjorn.andersson@...ymobile.com>
:::::: CC: Wolfram Sang <wsa@...-dreams.de>

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