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Date:   Mon, 15 Aug 2022 09:55:40 +0800
From:   kernel test robot <yujie.liu@...el.com>
To:     Hans Verkuil <hverkuil@...all.nl>
CC:     <llvm@...ts.linux.dev>, <kbuild-all@...ts.01.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: [hverkuil-media-tree:tegrav8 2/7]
 drivers/media/i2c/tc358840.c:1647:3: warning: Value stored to 'have_hdcp' is
 never read [clang-analyzer-deadcode.DeadStores]

tree:   git://linuxtv.org/hverkuil/media_tree.git tegrav8
head:   386823032a34ce7926c18033b0ca34de9145a206
commit: f51f9140626da0e72ade6bd437ac2fe13e9b0425 [2/7] tc358840: add Toshiba tc358840 HDMI-to-CSI bridge.
config: mips-randconfig-c004-20220808 (https://download.01.org/0day-ci/archive/20220813/202208131429.45nzEuBD-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 5f1c7e2cc5a3c07cbc2412e851a7283c1841f520)
reproduce (this is a W=1 build):
         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
         chmod +x ~/bin/make.cross
         # install mips cross compiling tool for clang build
         # apt-get install binutils-mipsel-linux-gnu
         git remote add hverkuil-media-tree git://linuxtv.org/hverkuil/media_tree.git
         git fetch --no-tags hverkuil-media-tree tegrav8
         git checkout f51f9140626da0e72ade6bd437ac2fe13e9b0425
         # save the config file
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips clang-analyzer

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <yujie.liu@...el.com>

clang-analyzer warnings: (new ones prefixed by >>)

 >> drivers/media/i2c/tc358840.c:1647:3: warning: Value stored to 'have_hdcp' is never read [clang-analyzer-deadcode.DeadStores]
                    have_hdcp = !(i2c_rd8(sd, HDCP_MODE) &
                    ^           ~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/have_hdcp +1647 drivers/media/i2c/tc358840.c

f51f9140626da0 Hans Verkuil 2020-02-21  1608
f51f9140626da0 Hans Verkuil 2020-02-21  1609  static void tc358840_delayed_work_poll(struct work_struct *work)
f51f9140626da0 Hans Verkuil 2020-02-21  1610  {
f51f9140626da0 Hans Verkuil 2020-02-21  1611  	struct delayed_work *dwork = to_delayed_work(work);
f51f9140626da0 Hans Verkuil 2020-02-21  1612  	struct tc358840_state *state = container_of(dwork,
f51f9140626da0 Hans Verkuil 2020-02-21  1613  		struct tc358840_state, delayed_work_poll);
f51f9140626da0 Hans Verkuil 2020-02-21  1614  	struct v4l2_subdev *sd = &state->sd;
f51f9140626da0 Hans Verkuil 2020-02-21  1615  	u8 sys_status;
f51f9140626da0 Hans Verkuil 2020-02-21  1616  	bool have_5v;
f51f9140626da0 Hans Verkuil 2020-02-21  1617  	bool have_tmds;
f51f9140626da0 Hans Verkuil 2020-02-21  1618  	bool have_sync;
f51f9140626da0 Hans Verkuil 2020-02-21  1619  	bool have_signal;
f51f9140626da0 Hans Verkuil 2020-02-21  1620  	bool have_hdcp;
f51f9140626da0 Hans Verkuil 2020-02-21  1621  	unsigned int format_change = 0;
f51f9140626da0 Hans Verkuil 2020-02-21  1622
f51f9140626da0 Hans Verkuil 2020-02-21  1623  	mutex_lock(&state->lock);
f51f9140626da0 Hans Verkuil 2020-02-21  1624
f51f9140626da0 Hans Verkuil 2020-02-21  1625  	sys_status = i2c_rd8(sd, SYS_STATUS);
f51f9140626da0 Hans Verkuil 2020-02-21  1626  	have_5v = state->test_pattern || (sys_status & MASK_S_DDC5V);
f51f9140626da0 Hans Verkuil 2020-02-21  1627  	have_tmds = state->test_pattern || (sys_status & MASK_S_TMDS);
f51f9140626da0 Hans Verkuil 2020-02-21  1628  	have_sync = state->test_pattern || (sys_status & MASK_S_SYNC);
f51f9140626da0 Hans Verkuil 2020-02-21  1629  	have_signal = have_5v && have_tmds && have_sync;
f51f9140626da0 Hans Verkuil 2020-02-21  1630  	have_hdcp = have_signal ? (sys_status & MASK_S_HDCP) : false;
f51f9140626da0 Hans Verkuil 2020-02-21  1631
f51f9140626da0 Hans Verkuil 2020-02-21  1632  	tc358840_check_5v(sd, have_5v);
f51f9140626da0 Hans Verkuil 2020-02-21  1633  	if (have_hdcp) {
f51f9140626da0 Hans Verkuil 2020-02-21  1634  		/*
f51f9140626da0 Hans Verkuil 2020-02-21  1635  		 * MASK_S_HDCP can be 1 for a short time when connecting
f51f9140626da0 Hans Verkuil 2020-02-21  1636  		 * or disconnecting: the HDCP authentication will kick in
f51f9140626da0 Hans Verkuil 2020-02-21  1637  		 * when that happens and thus MASK_S_HDCP becomes 1 until
f51f9140626da0 Hans Verkuil 2020-02-21  1638  		 * the authentication fails and it is cleared again.
f51f9140626da0 Hans Verkuil 2020-02-21  1639  		 *
f51f9140626da0 Hans Verkuil 2020-02-21  1640  		 * So if it is set, then double check that the HDCP_MODE
f51f9140626da0 Hans Verkuil 2020-02-21  1641  		 * is in manual authentication mode, because then we know
f51f9140626da0 Hans Verkuil 2020-02-21  1642  		 * the authentication will fail and this is just a glitch.
f51f9140626da0 Hans Verkuil 2020-02-21  1643  		 *
f51f9140626da0 Hans Verkuil 2020-02-21  1644  		 * Don't rely on some global setting, actually read the
f51f9140626da0 Hans Verkuil 2020-02-21  1645  		 * register here. This in case someone has been hacking.
f51f9140626da0 Hans Verkuil 2020-02-21  1646  		 */
f51f9140626da0 Hans Verkuil 2020-02-21 @1647  		have_hdcp = !(i2c_rd8(sd, HDCP_MODE) &
f51f9140626da0 Hans Verkuil 2020-02-21  1648  			      MASK_MANUAL_AUTHENTICATION);
f51f9140626da0 Hans Verkuil 2020-02-21  1649  	}
f51f9140626da0 Hans Verkuil 2020-02-21  1650
f51f9140626da0 Hans Verkuil 2020-02-21  1651  	if (!have_5v) {
f51f9140626da0 Hans Verkuil 2020-02-21  1652  		state->invalid_eq_bypass[0] = false;
f51f9140626da0 Hans Verkuil 2020-02-21  1653  		state->invalid_eq_bypass[1] = false;
f51f9140626da0 Hans Verkuil 2020-02-21  1654  	}
f51f9140626da0 Hans Verkuil 2020-02-21  1655  	if (state->test_pattern) {
f51f9140626da0 Hans Verkuil 2020-02-21  1656  		state->found_stable_signal = true;
f51f9140626da0 Hans Verkuil 2020-02-21  1657  		state->status = STATUS_STABLE_SIGNAL;
f51f9140626da0 Hans Verkuil 2020-02-21  1658  	} else {
f51f9140626da0 Hans Verkuil 2020-02-21  1659  		u8 sys_int = i2c_rd8(sd, SYS_INT);
f51f9140626da0 Hans Verkuil 2020-02-21  1660  		u8 clk_int = i2c_rd8(sd, CLK_INT);
f51f9140626da0 Hans Verkuil 2020-02-21  1661  		u8 misc_int = i2c_rd8(sd, MISC_INT);
f51f9140626da0 Hans Verkuil 2020-02-21  1662  		bool was_stable = state->found_stable_signal;
f51f9140626da0 Hans Verkuil 2020-02-21  1663
f51f9140626da0 Hans Verkuil 2020-02-21  1664  		i2c_wr8(sd, MISC_INT, 0xff);
f51f9140626da0 Hans Verkuil 2020-02-21  1665  		i2c_wr8(sd, CLK_INT, 0xff);
f51f9140626da0 Hans Verkuil 2020-02-21  1666  		i2c_wr8(sd, SYS_INT, 0xff);
f51f9140626da0 Hans Verkuil 2020-02-21  1667  		v4l2_dbg(2, debug, sd,
f51f9140626da0 Hans Verkuil 2020-02-21  1668  			 "%s: sys_stat: %02x misc_int: %02x clk_int: %02x sys_int: %02x eq_byps: %s\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1669  			 __func__, sys_status, misc_int, clk_int, sys_int,
f51f9140626da0 Hans Verkuil 2020-02-21  1670  			 state->eq_bypass ? "on" : "off");
f51f9140626da0 Hans Verkuil 2020-02-21  1671
f51f9140626da0 Hans Verkuil 2020-02-21  1672  		if (!have_sync)
f51f9140626da0 Hans Verkuil 2020-02-21  1673  			format_change |= 1;
f51f9140626da0 Hans Verkuil 2020-02-21  1674  		if (sys_int & (MASK_DVI | MASK_HDMI))
f51f9140626da0 Hans Verkuil 2020-02-21  1675  			format_change |= 2;
f51f9140626da0 Hans Verkuil 2020-02-21  1676  		if (clk_int & (MASK_IN_DE_CHG))
f51f9140626da0 Hans Verkuil 2020-02-21  1677  			format_change |= 4;
f51f9140626da0 Hans Verkuil 2020-02-21  1678  		if (misc_int & (MASK_SYNC_CHG))
f51f9140626da0 Hans Verkuil 2020-02-21  1679  			format_change |= 8;
f51f9140626da0 Hans Verkuil 2020-02-21  1680
f51f9140626da0 Hans Verkuil 2020-02-21  1681  		if (sys_int & MASK_HDMI) {
f51f9140626da0 Hans Verkuil 2020-02-21  1682  			v4l2_dbg(1, debug, sd, "%s: DVI->HDMI change detected\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1683  				 __func__);
f51f9140626da0 Hans Verkuil 2020-02-21  1684
f51f9140626da0 Hans Verkuil 2020-02-21  1685  			i2c_wr8(sd, APPL_CTL, MASK_APLL_CPCTL_NORMAL | MASK_APLL_ON);
f51f9140626da0 Hans Verkuil 2020-02-21  1686  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1687  		if (sys_int & MASK_DVI) {
f51f9140626da0 Hans Verkuil 2020-02-21  1688  			v4l2_dbg(1, debug, sd, "%s: HDMI->DVI change detected\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1689  				 __func__);
f51f9140626da0 Hans Verkuil 2020-02-21  1690  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1691  		if (!have_signal) {
f51f9140626da0 Hans Verkuil 2020-02-21  1692  			if (state->status != STATUS_FIND_SIGNAL)
f51f9140626da0 Hans Verkuil 2020-02-21  1693  				v4l2_info(sd, "no signal for EQ_BYPS %d\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1694  					  state->eq_bypass);
f51f9140626da0 Hans Verkuil 2020-02-21  1695  			state->status = STATUS_FIND_SIGNAL;
f51f9140626da0 Hans Verkuil 2020-02-21  1696  			state->found_signal_cnt[0] = 0;
f51f9140626da0 Hans Verkuil 2020-02-21  1697  			state->found_signal_cnt[1] = 0;
f51f9140626da0 Hans Verkuil 2020-02-21  1698  			if (state->enabled)
f51f9140626da0 Hans Verkuil 2020-02-21  1699  				enable_stream(sd, false);
f51f9140626da0 Hans Verkuil 2020-02-21  1700  			if (state->found_stable_signal) {
f51f9140626da0 Hans Verkuil 2020-02-21  1701  				state->found_stable_signal = false;
f51f9140626da0 Hans Verkuil 2020-02-21  1702  				v4l2_subdev_notify_event(sd, &tc358840_ev_fmt);
f51f9140626da0 Hans Verkuil 2020-02-21  1703  				v4l2_info(sd, "event: no signal (SYS_STATUS 0x%02x)\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1704  					  sys_status);
f51f9140626da0 Hans Verkuil 2020-02-21  1705  			}
f51f9140626da0 Hans Verkuil 2020-02-21  1706  			state->detected_timings.bt.width = 0;
f51f9140626da0 Hans Verkuil 2020-02-21  1707  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1708  		/*
f51f9140626da0 Hans Verkuil 2020-02-21  1709  		 * Reset the HDMI PHY to try to trigger proper lock on the
f51f9140626da0 Hans Verkuil 2020-02-21  1710  		 * incoming video format. Erase BKSV to prevent that old keys
f51f9140626da0 Hans Verkuil 2020-02-21  1711  		 * are used when a new source is connected.
f51f9140626da0 Hans Verkuil 2020-02-21  1712  		 */
f51f9140626da0 Hans Verkuil 2020-02-21  1713  		if (have_5v && (format_change & 0xa) && !have_signal) {
f51f9140626da0 Hans Verkuil 2020-02-21  1714  			if (have_tmds)
f51f9140626da0 Hans Verkuil 2020-02-21  1715  				v4l2_dbg(was_stable ? 0 : 1, debug, sd,
f51f9140626da0 Hans Verkuil 2020-02-21  1716  					 "reset due to format_change (%x)\n",
f51f9140626da0 Hans Verkuil 2020-02-21  1717  					 format_change);
f51f9140626da0 Hans Verkuil 2020-02-21  1718  			tc358840_reset_phy(sd);
f51f9140626da0 Hans Verkuil 2020-02-21  1719  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1720  	}
f51f9140626da0 Hans Verkuil 2020-02-21  1721
f51f9140626da0 Hans Verkuil 2020-02-21  1722  	if (have_signal) {
f51f9140626da0 Hans Verkuil 2020-02-21  1723  		struct v4l2_dv_timings timings = { };
f51f9140626da0 Hans Verkuil 2020-02-21  1724
f51f9140626da0 Hans Verkuil 2020-02-21  1725  		/*
f51f9140626da0 Hans Verkuil 2020-02-21  1726  		 * If we don't have detected_timings, or something changed, then
f51f9140626da0 Hans Verkuil 2020-02-21  1727  		 * detect timings.
f51f9140626da0 Hans Verkuil 2020-02-21  1728  		 */
f51f9140626da0 Hans Verkuil 2020-02-21  1729  		if (format_change || !state->detected_timings.bt.width)
f51f9140626da0 Hans Verkuil 2020-02-21  1730  			tc358840_get_detected_timings(sd, &timings);
f51f9140626da0 Hans Verkuil 2020-02-21  1731  		else
f51f9140626da0 Hans Verkuil 2020-02-21  1732  			timings = state->detected_timings;
f51f9140626da0 Hans Verkuil 2020-02-21  1733
f51f9140626da0 Hans Verkuil 2020-02-21  1734  		/*
f51f9140626da0 Hans Verkuil 2020-02-21  1735  		 * Store newly detected timings (if any) if we detect timings
f51f9140626da0 Hans Verkuil 2020-02-21  1736  		 * for the first time, or if the sync toggled, or if the
f51f9140626da0 Hans Verkuil 2020-02-21  1737  		 * DVI/HDMI mode changed.
f51f9140626da0 Hans Verkuil 2020-02-21  1738  		 */
f51f9140626da0 Hans Verkuil 2020-02-21  1739  		if (!state->detected_timings.bt.width || (format_change & 3)) {
f51f9140626da0 Hans Verkuil 2020-02-21  1740  			state->detected_timings = timings;
f51f9140626da0 Hans Verkuil 2020-02-21  1741  		/*
f51f9140626da0 Hans Verkuil 2020-02-21  1742  		 * Silently accept SYNC/DE changes if the timings stay the same,
f51f9140626da0 Hans Verkuil 2020-02-21  1743  		 * i.e. if only blanking changed.
f51f9140626da0 Hans Verkuil 2020-02-21  1744  		 */
f51f9140626da0 Hans Verkuil 2020-02-21  1745  		} else if (format_change &&
f51f9140626da0 Hans Verkuil 2020-02-21  1746  			   tc358840_match_dv_timings(&state->detected_timings,
f51f9140626da0 Hans Verkuil 2020-02-21  1747  						     &timings, 250000)) {
f51f9140626da0 Hans Verkuil 2020-02-21  1748  			v4l2_dbg(1, debug, sd, "ignore timings change\n");
f51f9140626da0 Hans Verkuil 2020-02-21  1749  			format_change = 0;
f51f9140626da0 Hans Verkuil 2020-02-21  1750  		} else {
f51f9140626da0 Hans Verkuil 2020-02-21  1751  			state->detected_timings = timings;
f51f9140626da0 Hans Verkuil 2020-02-21  1752  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1753  		have_signal = state->detected_timings.bt.width;
f51f9140626da0 Hans Verkuil 2020-02-21  1754  	}
f51f9140626da0 Hans Verkuil 2020-02-21  1755
f51f9140626da0 Hans Verkuil 2020-02-21  1756  	if (!state->test_pattern && have_5v) {
f51f9140626da0 Hans Verkuil 2020-02-21  1757  		switch (state->status) {
f51f9140626da0 Hans Verkuil 2020-02-21  1758  		case STATUS_FIND_SIGNAL:
f51f9140626da0 Hans Verkuil 2020-02-21  1759  			tc358840_find_signal(sd, have_signal);
f51f9140626da0 Hans Verkuil 2020-02-21  1760  			break;
f51f9140626da0 Hans Verkuil 2020-02-21  1761  		case STATUS_FOUND_SIGNAL:
f51f9140626da0 Hans Verkuil 2020-02-21  1762  			tc358840_found_signal(sd, have_signal, format_change);
f51f9140626da0 Hans Verkuil 2020-02-21  1763  			break;
f51f9140626da0 Hans Verkuil 2020-02-21  1764  		case STATUS_STABLE_SIGNAL:
f51f9140626da0 Hans Verkuil 2020-02-21  1765  			tc358840_format_change(sd, have_signal, format_change);
f51f9140626da0 Hans Verkuil 2020-02-21  1766  			break;
f51f9140626da0 Hans Verkuil 2020-02-21  1767  		}
f51f9140626da0 Hans Verkuil 2020-02-21  1768  	}
f51f9140626da0 Hans Verkuil 2020-02-21  1769  	mutex_unlock(&state->lock);
f51f9140626da0 Hans Verkuil 2020-02-21  1770  	v4l2_ctrl_s_ctrl(state->tmds_present_ctrl, have_signal);
f51f9140626da0 Hans Verkuil 2020-02-21  1771  	v4l2_ctrl_s_ctrl(state->detect_tx_5v_ctrl, have_5v);
f51f9140626da0 Hans Verkuil 2020-02-21  1772  	v4l2_ctrl_s_ctrl(state->audio_present_ctrl, audio_present(sd));
f51f9140626da0 Hans Verkuil 2020-02-21  1773
f51f9140626da0 Hans Verkuil 2020-02-21  1774  	if (have_signal)
f51f9140626da0 Hans Verkuil 2020-02-21  1775  		v4l2_ctrl_s_ctrl(state->audio_sampling_rate_ctrl,
f51f9140626da0 Hans Verkuil 2020-02-21  1776  				 get_audio_sampling_rate(sd));
f51f9140626da0 Hans Verkuil 2020-02-21  1777
f51f9140626da0 Hans Verkuil 2020-02-21  1778  	if (!state->delayed_work_stop_polling)
f51f9140626da0 Hans Verkuil 2020-02-21  1779  		schedule_delayed_work(&state->delayed_work_poll, POLL_PERIOD);
f51f9140626da0 Hans Verkuil 2020-02-21  1780  }
f51f9140626da0 Hans Verkuil 2020-02-21  1781

-- 
0-DAY CI Kernel Test Service
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