serial/arc-uart: Handle Rx Error Interrupts w/o any data

Currently, Rx error handling only triggers if there is some Rx data.
Fix that by checking for error - before the data handling.

Reported-by: Mischa Jonker <mjonker@synopsys.com>
Tested-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index 2f195f0d7a11cfb4ed476357f8c47febf17d6560..e296c892df6113ba0697f4931b0db66478308ac3 100644 (file)
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -209,9 +209,9 @@ static void arc_serial_start_tx(struct uart_port *port)
        arc_serial_tx_chars(uart);
 }
 
-static void arc_serial_rx_chars(struct arc_uart_port *uart)
+static void arc_serial_rx_chars(struct arc_uart_port *uart, unsigned int status)
 {
-       unsigned int status, ch, flg = 0;
+       unsigned int ch, flg = 0;
 
        /*
         * UART has 4 deep RX-FIFO. Driver's recongnition of this fact
@@ -222,11 +222,11 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)
         * before RX-EMPTY=0, implies some sort of buffering going on in the
         * controller, which is indeed the Rx-FIFO.
         */
-       while (!((status = UART_GET_STATUS(uart)) & RXEMPTY)) {
-
-               ch = UART_GET_DATA(uart);
-               uart->port.icount.rx++;
-
+       do {
+               /*
+                * This could be an Rx Intr for err (no data),
+                * so check err and clear that Intr first
+                */
                if (unlikely(status & (RXOERR | RXFERR))) {
                        if (status & RXOERR) {
                                uart->port.icount.overrun++;
@@ -242,6 +242,12 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)
                } else
                        flg = TTY_NORMAL;
 
+               if (status & RXEMPTY)
+                       continue;
+
+               ch = UART_GET_DATA(uart);
+               uart->port.icount.rx++;
+
                if (unlikely(uart_handle_sysrq_char(&uart->port, ch)))
                        goto done;
 
@@ -249,7 +255,7 @@ static void arc_serial_rx_chars(struct arc_uart_port *uart)
 
 done:
                tty_flip_buffer_push(&uart->port.state->port);
-       }
+       } while (!((status = UART_GET_STATUS(uart)) & RXEMPTY));
 }
 
 /*
@@ -292,11 +298,11 @@ static irqreturn_t arc_serial_isr(int irq, void *dev_id)
         * notifications from the UART Controller.
         * To demultiplex between the two, we check the relevant bits
         */
-       if ((status & RXIENB) && !(status & RXEMPTY)) {
+       if (status & RXIENB) {
 
                /* already in ISR, no need of xx_irqsave */
                spin_lock(&uart->port.lock);
-               arc_serial_rx_chars(uart);
+               arc_serial_rx_chars(uart, status);
                spin_unlock(&uart->port.lock);
        }