diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index b3abc29aa927..bb1a98c97adf 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -349,6 +349,13 @@ static inline void serial8250_do_prepare_rx_dma(struct uart_8250_port *p) if (dma->prepare_rx_dma) dma->prepare_rx_dma(p); } + +static inline bool serial8250_tx_dma_running(struct uart_8250_port *p) +{ + struct uart_8250_dma *dma = p->dma; + + return dma && dma->tx_running; +} #else static inline int serial8250_tx_dma(struct uart_8250_port *p) { @@ -364,6 +371,11 @@ static inline int serial8250_request_dma(struct uart_8250_port *p) return -1; } static inline void serial8250_release_dma(struct uart_8250_port *p) { } + +static inline bool serial8250_tx_dma_running(struct uart_8250_port *p) +{ + return false; +} #endif static inline int ns16550a_goto_highspeed(struct uart_8250_port *up) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 5939f510cb0c..bfdd9ecc2baf 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1988,19 +1988,25 @@ static int serial8250_tx_threshold_handle_irq(struct uart_port *port) static unsigned int serial8250_tx_empty(struct uart_port *port) { struct uart_8250_port *up = up_to_u8250p(port); + unsigned int result = 0; unsigned long flags; unsigned int lsr; serial8250_rpm_get(up); spin_lock_irqsave(&port->lock, flags); - lsr = serial_port_in(port, UART_LSR); - up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; + if (!serial8250_tx_dma_running(up)) { + lsr = serial_port_in(port, UART_LSR); + up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; + + if ((lsr & BOTH_EMPTY) == BOTH_EMPTY) + result = TIOCSER_TEMT; + } spin_unlock_irqrestore(&port->lock, flags); serial8250_rpm_put(up); - return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0; + return result; } unsigned int serial8250_do_get_mctrl(struct uart_port *port)