tree: https://android.googlesource.com/kernel/common android-3.18 head: 4ab5ed1b2426544d8c587343973654305580d2f7 commit: e6987658af51adc475e3769d466a739d753134bd [143/170] tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped config: arm-at91_dt_defconfig (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 5.5.0 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 git remote add android-common https://android.googlesource.com/kernel/common git fetch --no-tags android-common android-3.18 git checkout e6987658af51adc475e3769d466a739d753134bd # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-5.5.0 make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/linux/dma-mapping.h:82:0, from drivers/tty/serial/atmel_serial.c:39: arch/arm/include/asm/dma-mapping.h: In function 'dma_mapping_error': arch/arm/include/asm/dma-mapping.h:170:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return dma_addr == DMA_ERROR_CODE; ^ drivers/tty/serial/atmel_serial.c: At top level: drivers/tty/serial/atmel_serial.c:296:6: warning: no previous declaration for 'atmel_config_rs485' [-Wmissing-declarations] void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) ^ drivers/tty/serial/atmel_serial.c: In function 'atmel_complete_tx_dma': atmel_uart_writel(port, ATMEL_US_IER, ^ drivers/tty/serial/atmel_serial.c: In function 'atmel_rx_from_dma': drivers/tty/serial/atmel_serial.c:972:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pending > ring->head) { ^ drivers/tty/serial/atmel_serial.c:978:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (ring->head == sg_dma_len(&atmel_port->sg_rx)) ^ drivers/tty/serial/atmel_serial.c: In function 'atmel_handle_transmit': if (!(atmel_uart_readl(port, ATMEL_US_CSR) ^ drivers/tty/serial/atmel_serial.c: In function 'atmel_verify_port': drivers/tty/serial/atmel_serial.c:2145:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (port->irq != ser->irq) ^ drivers/tty/serial/atmel_serial.c:2149:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (port->uartclk / 16 != ser->baud_base) ^ drivers/tty/serial/atmel_serial.c: In function 'atmel_is_console_port': drivers/tty/serial/atmel_serial.c:2475:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return port->cons && port->cons->index == port->line; ^ cc1: some warnings being treated as errors vim +/atmel_uart_writel +745 drivers/tty/serial/atmel_serial.c 708 709 static void atmel_complete_tx_dma(void *arg) 710 { 711 struct atmel_uart_port *atmel_port = arg; 712 struct uart_port *port = &atmel_port->uart; 713 struct circ_buf *xmit = &port->state->xmit; 714 struct dma_chan *chan = atmel_port->chan_tx; 715 unsigned long flags; 716 717 spin_lock_irqsave(&port->lock, flags); 718 719 if (chan) 720 dmaengine_terminate_all(chan); 721 xmit->tail += sg_dma_len(&atmel_port->sg_tx); 722 xmit->tail &= UART_XMIT_SIZE - 1; 723 724 port->icount.tx += sg_dma_len(&atmel_port->sg_tx); 725 726 spin_lock_irq(&atmel_port->lock_tx); 727 async_tx_ack(atmel_port->desc_tx); 728 atmel_port->cookie_tx = -EINVAL; 729 atmel_port->desc_tx = NULL; 730 spin_unlock_irq(&atmel_port->lock_tx); 731 732 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) 733 uart_write_wakeup(port); 734 735 /* Do we really need this? */ 736 if (!uart_circ_empty(xmit)) 737 tasklet_schedule(&atmel_port->tasklet); 738 else if ((atmel_port->rs485.flags & SER_RS485_ENABLED) && 739 !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) { 740 /* 741 * DMA done, re-enable TXEMPTY and signal that we can stop 742 * TX and start RX for RS485 743 */ 744 atmel_port->hd_start_rx = true; 746 atmel_port->tx_done_mask); 747 } 748 749 spin_unlock_irqrestore(&port->lock, flags); 750 } 751 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org