When a break signal is detected, the next character should be ignored.

This was not implemented correctly for the pnx8xxx_uart driver.

[From further discussion:
Correct, you can look to it as two separate bugs:
a) the next character is not ignored while it should;
b) the status bits 31-8 are copied to the 'ch' variable while they shouldn't.

Both bugs prevent correct break signal handling (and therefore correct
behaviour of the magic SysRq key). Bug b didn't cause too much trouble
earlier because in most situations the status bits are all zero; for
this case they unfortunately aren't.
]

Signed-off-by: Mischa Jonker <mischa.jonker@nxp.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 11 deletions

diff --git a/drivers/serial/pnx8xxx_uart.c b/drivers/serial/pnx8xxx_uart.c
index 22e30d21225e..1bb8f1b45767 100644
--- a/drivers/serial/pnx8xxx_uart.c
+++ b/drivers/serial/pnx8xxx_uart.c
@@ -187,7 +187,7 @@ static void pnx8xxx_rx_chars(struct pnx8xxx_port *sport)
         status = FIFO_TO_SM(serial_in(sport, PNX8XXX_FIFO)) |
                  ISTAT_TO_SM(serial_in(sport, PNX8XXX_ISTAT));
         while (status & FIFO_TO_SM(PNX8XXX_UART_FIFO_RXFIFO)) {
-                ch = serial_in(sport, PNX8XXX_FIFO);
+                ch = serial_in(sport, PNX8XXX_FIFO) & 0xff;
 
                 sport->port.icount.rx++;
 
@@ -198,9 +198,16 @@ static void pnx8xxx_rx_chars(struct pnx8xxx_port *sport)
                  * out of the main execution path
                  */
                 if (status & (FIFO_TO_SM(PNX8XXX_UART_FIFO_RXFE |
-                                        PNX8XXX_UART_FIFO_RXPAR) |
+                                        PNX8XXX_UART_FIFO_RXPAR |
+                                        PNX8XXX_UART_FIFO_RXBRK) |
                               ISTAT_TO_SM(PNX8XXX_UART_INT_RXOVRN))) {
-                        if (status & FIFO_TO_SM(PNX8XXX_UART_FIFO_RXPAR))
+                        if (status & FIFO_TO_SM(PNX8XXX_UART_FIFO_RXBRK)) {
+                                status &= ~(FIFO_TO_SM(PNX8XXX_UART_FIFO_RXFE) |
+                                        FIFO_TO_SM(PNX8XXX_UART_FIFO_RXPAR));
+                                sport->port.icount.brk++;
+                                if (uart_handle_break(&sport->port))
+                                        goto ignore_char;
+                        } else if (status & FIFO_TO_SM(PNX8XXX_UART_FIFO_RXPAR))
                                 sport->port.icount.parity++;
                         else if (status & FIFO_TO_SM(PNX8XXX_UART_FIFO_RXFE))
                                 sport->port.icount.frame++;
@@ -284,14 +291,8 @@ static irqreturn_t pnx8xxx_int(int irq, void *dev_id)
         /* Get the interrupts */
         status  = serial_in(sport, PNX8XXX_ISTAT) & serial_in(sport, PNX8XXX_IEN);
 
-        /* Break signal received */
-        if (status & PNX8XXX_UART_INT_BREAK) {
-                sport->port.icount.brk++;
-                uart_handle_break(&sport->port);
-        }
-
-        /* Byte received */
-        if (status & PNX8XXX_UART_INT_RX)
+        /* Byte or break signal received */
+        if (status & (PNX8XXX_UART_INT_RX | PNX8XXX_UART_INT_BREAK))
                 pnx8xxx_rx_chars(sport);
 
         /* TX holding register empty - transmit a byte */