Re: [PATCH v3] can: m_can: don't enable transceiver when probing

[kernel test robot]

Hi Martin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on mkl-can-next/testing]
[also build test WARNING on linus/master v6.10-rc1 next-20240529]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Martin-Hundeb-ll/can-m_can-don-t-enable-transceiver-when-probing/20240530-185906
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git testing
patch link:    https://lore.kernel.org/r/20240530105801.3930087-1-martin%40geanix.com
patch subject: [PATCH v3] can: m_can: don't enable transceiver when probing
config: i386-buildonly-randconfig-003-20240530 (https://download.01.org/0day-ci/archive/20240530/202405302307.MKjlGruk-lkp@xxxxxxxxx/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240530/202405302307.MKjlGruk-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405302307.MKjlGruk-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> drivers/net/can/m_can/m_can.c:1725:11: warning: variable 'err' is uninitialized when used here [-Wuninitialized]
    1725 |                         return err;
         |                                ^~~
   drivers/net/can/m_can/m_can.c:1674:24: note: initialize the variable 'err' to silence this warning
    1674 |         int m_can_version, err, niso;
         |                               ^
         |                                = 0
   1 warning generated.


vim +/err +1725 drivers/net/can/m_can/m_can.c

  1670	
  1671	static int m_can_dev_setup(struct m_can_classdev *cdev)
  1672	{
  1673		struct net_device *dev = cdev->net;
  1674		int m_can_version, err, niso;
  1675	
  1676		m_can_version = m_can_check_core_release(cdev);
  1677		/* return if unsupported version */
  1678		if (!m_can_version) {
  1679			dev_err(cdev->dev, "Unsupported version number: %2d",
  1680				m_can_version);
  1681			return -EINVAL;
  1682		}
  1683	
  1684		if (!cdev->is_peripheral)
  1685			netif_napi_add(dev, &cdev->napi, m_can_poll);
  1686	
  1687		/* Shared properties of all M_CAN versions */
  1688		cdev->version = m_can_version;
  1689		cdev->can.do_set_mode = m_can_set_mode;
  1690		cdev->can.do_get_berr_counter = m_can_get_berr_counter;
  1691	
  1692		/* Set M_CAN supported operations */
  1693		cdev->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
  1694			CAN_CTRLMODE_LISTENONLY |
  1695			CAN_CTRLMODE_BERR_REPORTING |
  1696			CAN_CTRLMODE_FD |
  1697			CAN_CTRLMODE_ONE_SHOT;
  1698	
  1699		/* Set properties depending on M_CAN version */
  1700		switch (cdev->version) {
  1701		case 30:
  1702			/* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.0.x */
  1703			err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
  1704			if (err)
  1705				return err;
  1706			cdev->can.bittiming_const = &m_can_bittiming_const_30X;
  1707			cdev->can.data_bittiming_const = &m_can_data_bittiming_const_30X;
  1708			break;
  1709		case 31:
  1710			/* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.1.x */
  1711			err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
  1712			if (err)
  1713				return err;
  1714			cdev->can.bittiming_const = &m_can_bittiming_const_31X;
  1715			cdev->can.data_bittiming_const = &m_can_data_bittiming_const_31X;
  1716			break;
  1717		case 32:
  1718		case 33:
  1719			/* Support both MCAN version v3.2.x and v3.3.0 */
  1720			cdev->can.bittiming_const = &m_can_bittiming_const_31X;
  1721			cdev->can.data_bittiming_const = &m_can_data_bittiming_const_31X;
  1722	
  1723			niso = m_can_niso_supported(cdev);
  1724			if (niso < 0)
> 1725				return err;
  1726			if (niso)
  1727				cdev->can.ctrlmode_supported |= CAN_CTRLMODE_FD_NON_ISO;
  1728			break;
  1729		default:
  1730			dev_err(cdev->dev, "Unsupported version number: %2d",
  1731				cdev->version);
  1732			return -EINVAL;
  1733		}
  1734	
  1735		/* Forcing standby mode should be redunant, as the chip should be in
  1736		 * standby after a reset. Write the INIT bit anyways, should the chip
  1737		 * be configured by previous stage.
  1738		 */
  1739		return m_can_cccr_update_bits(cdev, CCCR_INIT, CCCR_INIT);
  1740	}
  1741	

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