MSM_UART_IMR_TXLEV
msm_port->imr &= ~MSM_UART_IMR_TXLEV;
msm_port->imr |= MSM_UART_IMR_TXLEV;
msm_port->imr |= MSM_UART_IMR_TXLEV;
msm_port->imr &= ~MSM_UART_IMR_TXLEV;
if (misr & MSM_UART_IMR_TXLEV)