Hello, I have a question about UART3 of DbAu1100. After enabling UART3 then reboot the kernel, I cannot use UART3 port. Did anyone encounter the same error ? In addition, UART3 initialization processing is as follows. static int serial_init (void) { volatile u32 *uart_fifoctl = (volatile u32*)(UART3_ADDR+UART_FCR); volatile u32 *uart_enable = (volatile u32*)(UART3_ADDR+UART_ENABLE); volatile u32 *uart_mcr = (volatile u32*)(UART3_ADDR+UART_MCR); volatile u32 *sys_pinfunc = (volatile u32*)SYS_PINFUNC; /* reset UART0 module */ au_writel(0x00, UART3_ADDR); au_sync( ); /* Enable clocks first */ *uart_enable = UART_EN_CE; /* Then release reset */ /* Must release reset before setting other regs */ *uart_enable = UART_EN_CE|UART_EN_E; /* Activate fifos, reset tx and rx */ /* Set tx trigger level to 12 */ *uart_fifoctl = UART_FCR_ENABLE_FIFO|UART_FCR_CLEAR_RCVR| UART_FCR_CLEAR_XMIT|UART_FCR_T_TRIGGER_12|UART_FCR_R_TRIGGER_14; serial_setbrg( ); /* Set DTR */ *uart_mcr = UART_MCR_DTR | UART_MCR_RTS; return 0; } static void serial_setbrg (void) { volatile u32 *uart_clk = (volatile u32*)(UART3_ADDR+UART_CLK); volatile u32 *uart_lcr = (volatile u32*)(UART3_ADDR+UART_LCR); /* Set baudrate to 9600 */ *uart_clk = 0x280; /* Set parity, stop bits and word length to 8N1 */ *uart_lcr = UART_LCR_WLEN8; return ; } Best regards, Nyauyama.