[PATCH] serial: pnx8xxx_uart: Fix break signal handling

[PATCH] serial: pnx8xxx_uart: Fix break signal handling

[Jonker M.D.S.X.]

From: Mischa Jonker <mischa.jonker@nxp.com>

When a break signal is detected, the next character should be ignored.
This was not implemented correctly for the pnx8xxx_uart driver.

Signed-off-by: Mischa Jonker <mischa.jonker@nxp.com>
---

diff --git a/drivers/serial/pnx8xxx_uart.c b/drivers/serial/pnx8xxx_uart.c
index 22e30d2..1bb8f1b 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 */

Re: [PATCH] serial: pnx8xxx_uart: Fix break signal handling

[Alan Cox]

On Tue, 13 Jan 2009 12:09:13 +0100
"Jonker M.D.S.X." <nlv14114@e3.nl-htc01.nxp.com> wrote:

> From: Mischa Jonker <mischa.jonker@nxp.com>
> 
> When a break signal is detected, the next character should be ignored.
> This was not implemented correctly for the pnx8xxx_uart driver.
> 
> Signed-off-by: Mischa Jonker <mischa.jonker@nxp.com>
> ---
> 
> diff --git a/drivers/serial/pnx8xxx_uart.c b/drivers/serial/pnx8xxx_uart.c
> index 22e30d2..1bb8f1b 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;

This appears to be unrelated.

Re: [PATCH] serial: pnx8xxx_uart: Fix break signal handling

[Mischa Jonker]

On Tue, Jan 13, 2009 at 1:11 PM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Tue, 13 Jan 2009 12:09:13 +0100
> "Jonker M.D.S.X." <nlv14114@e3.nl-htc01.nxp.com> wrote:
>
>> From: Mischa Jonker <mischa.jonker@nxp.com>
>>
>> When a break signal is detected, the next character should be ignored.
>> This was not implemented correctly for the pnx8xxx_uart driver.
>>
>> Signed-off-by: Mischa Jonker <mischa.jonker@nxp.com>
>> ---
>>
>> diff --git a/drivers/serial/pnx8xxx_uart.c b/drivers/serial/pnx8xxx_uart.c
>> index 22e30d2..1bb8f1b 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;
>
> This appears to be unrelated.
>

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.

I can split them up if you like, or we can keep them together, as they
are in fact related.

Thanks,

Mischa Jonker

Re: [PATCH] serial: pnx8xxx_uart: Fix break signal handling

[Alan Cox]

> > This appears to be unrelated.
> >
> 
> 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.

Ok that makes sense - no need to split them.