| Message ID | 20200928144127.87156-1-aabyzov@slb.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] serial: 8250_fsl: Fix TX interrupt handling condition | expand |
diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c index 0d0c80905c58..ceac6cfce4c7 100644 --- a/drivers/tty/serial/8250/8250_fsl.c +++ b/drivers/tty/serial/8250/8250_fsl.c @@ -71,7 +71,7 @@ int fsl8250_handle_irq(struct uart_port *port) serial8250_modem_status(up); - if (lsr & UART_LSR_THRE) + if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI)) serial8250_tx_chars(up); up->lsr_saved_flags = orig_lsr;
This is the port of the commit db1b5bc047b3 ("serial: 8250: Fix TX interrupt handling condition") to the 8250_fsl irq handling logic. Interrupt handler checked THRE bit (transmitter holding register empty) in LSR to detect if TX fifo is empty. In case when there is only receive interrupts the TX handling got called because THRE bit in LSR is set when there is no transmission (FIFO empty). TX handling caused TX stop, which in RS-485 half-duplex mode actually resets receiver FIFO. This is not desired during reception because of possible data loss. The fix is to check if THRI is set in IER in addition of the TX fifo status. THRI in IER is set when TX is started and cleared when TX is stopped. This ensures that TX handling is only called when there is really transmission on going and an interrupt for THRE and not when there are only RX interrupts. Signed-off-by: Andrij Abyzov <aabyzov@slb.com> --- Changes in v3: - Added change history Changes in v2: - Rewritten commit description drivers/tty/serial/8250/8250_fsl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)