Re: [PATCH v6 8/8] tty: i3c: add TTY over I3C master support

[kernel test robot]

Hi Frank,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tty/tty-testing]
[also build test WARNING on tty/tty-next tty/tty-linus robh/for-next linus/master v6.8-rc3 next-20240205]
[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/Frank-Li/i3c-add-target-mode-support/20240203-071519
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
patch link:    https://lore.kernel.org/r/20240202230925.1000659-9-Frank.Li%40nxp.com
patch subject: [PATCH v6 8/8] tty: i3c: add TTY over I3C master support
config: powerpc-randconfig-r071-20240205 (https://download.01.org/0day-ci/archive/20240205/202402052026.UNrmrB2M-lkp@xxxxxxxxx/config)
compiler: powerpc-linux-gcc (GCC) 13.2.0

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/202402052026.UNrmrB2M-lkp@xxxxxxxxx/

smatch warnings:
drivers/tty/i3c_tty.c:237 tty_i3c_rxwork() error: uninitialized symbol 'status'.

vim +/status +237 drivers/tty/i3c_tty.c

   191	
   192	static void tty_i3c_rxwork(struct work_struct *work)
   193	{
   194		struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, rxwork);
   195		struct i3c_priv_xfer xfers;
   196		u32 retry = I3C_TTY_RETRY;
   197		u16 status;
   198		int ret;
   199	
   200		memset(&xfers, 0, sizeof(xfers));
   201		xfers.data.in = sport->rx_buff;
   202		xfers.len = I3C_TTY_TRANS_SIZE;
   203		xfers.rnw = 1;
   204	
   205		do {
   206			if (test_bit(I3C_TTY_RX_STOP, &sport->status))
   207				break;
   208	
   209			i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1);
   210	
   211			if (xfers.actual_len) {
   212				ret = tty_insert_flip_string(&sport->port, sport->rx_buff,
   213							     xfers.actual_len);
   214				if (ret < xfers.actual_len)
   215					sport->buf_overrun++;
   216	
   217				retry = I3C_TTY_RETRY;
   218				continue;
   219			}
   220	
   221			status = I3C_TTY_TARGET_RX_READY;
   222			i3c_device_getstatus_format1(sport->i3cdev, &status);
   223			/*
   224			 * Target side needs some time to fill data into fifo. Target side may not
   225			 * have hardware update status in real time. Software update status always
   226			 * needs some delays.
   227			 *
   228			 * Generally, target side have circular buffer in memory, it will be moved
   229			 * into FIFO by CPU or DMA. 'status' just show if circular buffer empty. But
   230			 * there are gap, especially CPU have not response irq to fill FIFO in time.
   231			 * So xfers.actual will be zero, wait for little time to avoid flood
   232			 * transfer in i3c bus.
   233			 */
   234			usleep_range(I3C_TTY_YIELD_US, 10 * I3C_TTY_YIELD_US);
   235			retry--;
   236	
 > 237		} while (retry && (status & I3C_TTY_TARGET_RX_READY));
   238	
   239		tty_flip_buffer_push(&sport->port);
   240	}
   241	

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