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Groups > linux.kernel > #1208424 > unrolled thread

[PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity

Started byMichal Simek <michal.simek@xilinx.com>
First post2015-08-17 09:30 +0200
Last post2015-08-17 18:30 +0200
Articles 6 — 2 participants

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  [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity Michal Simek <michal.simek@xilinx.com> - 2015-08-17 09:30 +0200
    [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic Michal Simek <michal.simek@xilinx.com> - 2015-08-17 09:30 +0200
      Re: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic Peter Hurley <peter@hurleysoftware.com> - 2015-08-17 18:00 +0200
        Re: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic Peter Hurley <peter@hurleysoftware.com> - 2015-08-17 20:50 +0200
    Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd  parity Peter Hurley <peter@hurleysoftware.com> - 2015-08-17 17:40 +0200
      Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd  parity Peter Hurley <peter@hurleysoftware.com> - 2015-08-17 18:30 +0200

#1208424 — [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity

FromMichal Simek <michal.simek@xilinx.com>
Date2015-08-17 09:30 +0200
Subject[PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity
Message-ID<pYn1L-tt-3@gated-at.bofh.it>
From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>

Existing set_termios does not handle the option for enabling
odd parity. This patch fixes it.

Signed-off-by: Anirudha Sarangi <anirudh@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

 drivers/tty/serial/xilinx_uartps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 009e0dbc12d2..a3020344ac9d 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -723,7 +723,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
 	else
 		cval |= CDNS_UART_MR_STOPMODE_1_BIT; /* 1 STOP bit */
 
-	if (termios->c_cflag & PARENB) {
+	if ((termios->c_cflag & PARENB) || (termios->c_cflag & PARODD)) {
 		/* Mark or Space parity */
 		if (termios->c_cflag & CMSPAR) {
 			if (termios->c_cflag & PARODD)
-- 
2.3.5

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#1208427 — [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic

FromMichal Simek <michal.simek@xilinx.com>
Date2015-08-17 09:30 +0200
Subject[PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic
Message-ID<pYn1M-tt-17@gated-at.bofh.it>
In reply to#1208424
From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>

The existing interrupt handling logic has followins issues.
- Upon a parity error with default configuration, the control
  never comes out of the ISR thereby hanging Linux.
- The error handling logic around framing and parity error are buggy.
  There are chances that the errors will never be captured.
- The existing ISR is just too long.
This patch fixes all these concerns. It separates out the Tx and Rx
hanling logic into separate functions. It ensures that the status
registers are cleared on all cases so that a hang situation never
arises.

Signed-off-by: Anirudha Sarangi <anirudh@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

 drivers/tty/serial/xilinx_uartps.c | 194 ++++++++++++++++++++-----------------
 1 file changed, 104 insertions(+), 90 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2dc26e5f1384..c771dbbf6161 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -173,61 +173,86 @@ struct cdns_uart {
 		clk_rate_change_nb);
 
 /**
- * cdns_uart_isr - Interrupt handler
- * @irq: Irq number
- * @dev_id: Id of the port
- *
- * Return: IRQHANDLED
+ * cdns_uart_handle_tx - Handle the bytes to be Txed.
+ * @dev_id: Id of the UART port
+ * Return: None
  */
-static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
+static void cdns_uart_handle_tx(void *dev_id)
 {
 	struct uart_port *port = (struct uart_port *)dev_id;
-	unsigned long flags;
-	unsigned int isrstatus, numbytes;
-	unsigned int data;
-	char status = TTY_NORMAL;
+	unsigned int numbytes;
 
-	spin_lock_irqsave(&port->lock, flags);
+	if (uart_circ_empty(&port->state->xmit)) {
+		writel(CDNS_UART_IXR_TXEMPTY, port->membase +
+		       CDNS_UART_IDR_OFFSET);
+	} else {
+		numbytes = port->fifosize;
+		/* Break if no more data available in the UART buffer */
+		while (numbytes--) {
+			if (uart_circ_empty(&port->state->xmit))
+				break;
+			/*
+			 * Get the data from the UART circular buffer
+			 * and write it to the cdns_uart's TX_FIFO
+			 * register.
+			 */
+			writel(port->state->xmit.buf[port->state->xmit.tail],
+			       port->membase + CDNS_UART_FIFO_OFFSET);
 
-	/* Read the interrupt status register to determine which
-	 * interrupt(s) is/are active.
-	 */
-	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
+			port->icount.tx++;
 
-	/*
-	 * There is no hardware break detection, so we interpret framing
-	 * error with all-zeros data as a break sequence. Most of the time,
-	 * there's another non-zero byte at the end of the sequence.
-	 */
-	if (isrstatus & CDNS_UART_IXR_FRAMING) {
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-					CDNS_UART_SR_RXEMPTY)) {
-			if (!readl(port->membase + CDNS_UART_FIFO_OFFSET)) {
-				port->read_status_mask |= CDNS_UART_IXR_BRK;
-				isrstatus &= ~CDNS_UART_IXR_FRAMING;
-			}
+			/*
+			 * Adjust the tail of the UART buffer and wrap
+			 * the buffer if it reaches limit.
+			 */
+			port->state->xmit.tail =
+				(port->state->xmit.tail + 1) &
+					(UART_XMIT_SIZE - 1);
 		}
-		writel(CDNS_UART_IXR_FRAMING,
-				port->membase + CDNS_UART_ISR_OFFSET);
-	}
 
-	/* drop byte with parity error if IGNPAR specified */
-	if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
-		isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);
+		if (uart_circ_chars_pending(
+				&port->state->xmit) < WAKEUP_CHARS)
+			uart_write_wakeup(port);
+	}
+}
 
-	isrstatus &= port->read_status_mask;
-	isrstatus &= ~port->ignore_status_mask;
+/**
+ * cdns_uart_handle_rx - Handle the received bytes along with Rx errors.
+ * @dev_id: Id of the UART port
+ * @isrstatus: The interrupt status register value as read
+ * Return: None
+ */
+static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
+{
+	struct uart_port *port = (struct uart_port *)dev_id;
+	unsigned int data;
+	unsigned int framerrprocessed = 0;
+	char status = TTY_NORMAL;
 
-	if ((isrstatus & CDNS_UART_IXR_TOUT) ||
-		(isrstatus & CDNS_UART_IXR_RXTRIG)) {
-		/* Receive Timeout Interrupt */
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-					CDNS_UART_SR_RXEMPTY)) {
-			data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+	while ((readl(port->membase + CDNS_UART_SR_OFFSET) &
+		CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
+		data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+		port->icount.rx++;
+		/*
+		 * There is no hardware break detection, so we interpret
+		 * framing error with all-zeros data as a break sequence.
+		 * Most of the time, there's another non-zero byte at the
+		 * end of the sequence.
+		 */
+		if (isrstatus & CDNS_UART_IXR_FRAMING) {
+			if (!data) {
+				port->read_status_mask |= CDNS_UART_IXR_BRK;
+				framerrprocessed = 1;
+				continue;
+			}
+		}
+		isrstatus &= port->read_status_mask;
+		isrstatus &= ~port->ignore_status_mask;
 
-			/* Non-NULL byte after BREAK is garbage (99%) */
-			if (data && (port->read_status_mask &
-						CDNS_UART_IXR_BRK)) {
+		if ((isrstatus & CDNS_UART_IXR_TOUT) ||
+		    (isrstatus & CDNS_UART_IXR_RXTRIG)) {
+			if (data &&
+			    (port->read_status_mask & CDNS_UART_IXR_BRK)) {
 				port->read_status_mask &= ~CDNS_UART_IXR_BRK;
 				port->icount.brk++;
 				if (uart_handle_break(port))
@@ -249,67 +274,56 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 				spin_lock(&port->lock);
 			}
 #endif
-
-			port->icount.rx++;
-
 			if (isrstatus & CDNS_UART_IXR_PARITY) {
 				port->icount.parity++;
 				status = TTY_PARITY;
-			} else if (isrstatus & CDNS_UART_IXR_FRAMING) {
+			}
+			if ((isrstatus & CDNS_UART_IXR_FRAMING) &&
+			    !framerrprocessed) {
 				port->icount.frame++;
 				status = TTY_FRAME;
-			} else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
+			}
+			if (isrstatus & CDNS_UART_IXR_OVERRUN) {
 				port->icount.overrun++;
+				tty_insert_flip_char(&port->state->port, 0,
+						     TTY_OVERRUN);
 			}
-
-			uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
-					data, status);
+			tty_insert_flip_char(&port->state->port, data, status);
 		}
-		spin_unlock(&port->lock);
-		tty_flip_buffer_push(&port->state->port);
-		spin_lock(&port->lock);
 	}
+	spin_unlock(&port->lock);
+	tty_flip_buffer_push(&port->state->port);
+	spin_lock(&port->lock);
+}
 
-	/* Dispatch an appropriate handler */
-	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
-		if (uart_circ_empty(&port->state->xmit)) {
-			writel(CDNS_UART_IXR_TXEMPTY,
-					port->membase + CDNS_UART_IDR_OFFSET);
-		} else {
-			numbytes = port->fifosize;
-			/* Break if no more data available in the UART buffer */
-			while (numbytes--) {
-				if (uart_circ_empty(&port->state->xmit))
-					break;
-				/* Get the data from the UART circular buffer
-				 * and write it to the cdns_uart's TX_FIFO
-				 * register.
-				 */
-				writel(port->state->xmit.buf[
-						port->state->xmit.tail],
-					port->membase + CDNS_UART_FIFO_OFFSET);
-
-				port->icount.tx++;
-
-				/* Adjust the tail of the UART buffer and wrap
-				 * the buffer if it reaches limit.
-				 */
-				port->state->xmit.tail =
-					(port->state->xmit.tail + 1) &
-						(UART_XMIT_SIZE - 1);
-			}
+/**
+ * cdns_uart_isr - Interrupt handler
+ * @irq: Irq number
+ * @dev_id: Id of the port
+ *
+ * Return: IRQHANDLED
+ */
+static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
+{
+	struct uart_port *port = (struct uart_port *)dev_id;
+	unsigned int isrstatus;
 
-			if (uart_circ_chars_pending(
-					&port->state->xmit) < WAKEUP_CHARS)
-				uart_write_wakeup(port);
-		}
-	}
+	spin_lock(&port->lock);
 
+	/* Read the interrupt status register to determine which
+	 * interrupt(s) is/are active and clear them.
+	 */
+	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
 	writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
 
-	/* be sure to release the lock and tty before leaving */
-	spin_unlock_irqrestore(&port->lock, flags);
+	if (isrstatus & CDNS_UART_IXR_TXEMPTY) {
+		cdns_uart_handle_tx(dev_id);
+		isrstatus &= ~CDNS_UART_IXR_TXEMPTY;
+	}
+	if (isrstatus & CDNS_UART_IXR_MASK)
+		cdns_uart_handle_rx(dev_id, isrstatus);
 
+	spin_unlock(&port->lock);
 	return IRQ_HANDLED;
 }
 
-- 
2.3.5

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#1208670 — Re: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic

FromPeter Hurley <peter@hurleysoftware.com>
Date2015-08-17 18:00 +0200
SubjectRe: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic
Message-ID<pYuZj-3nQ-1@gated-at.bofh.it>
In reply to#1208427
On 08/17/2015 03:22 AM, Michal Simek wrote:
> From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>
> 
> The existing interrupt handling logic has followins issues.
> - Upon a parity error with default configuration, the control
>   never comes out of the ISR thereby hanging Linux.
> - The error handling logic around framing and parity error are buggy.
>   There are chances that the errors will never be captured.
> - The existing ISR is just too long.
> This patch fixes all these concerns.

This patch is unreviewable. Please break this down into multiple patches.

Regards,
Peter Hurley

> It separates out the Tx and Rx
> hanling logic into separate functions. It ensures that the status
> registers are cleared on all cases so that a hang situation never
> arises.
> 
> Signed-off-by: Anirudha Sarangi <anirudh@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> ---
> 
>  drivers/tty/serial/xilinx_uartps.c | 194 ++++++++++++++++++++-----------------
>  1 file changed, 104 insertions(+), 90 deletions(-)
> 
> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
> index 2dc26e5f1384..c771dbbf6161 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -173,61 +173,86 @@ struct cdns_uart {
>  		clk_rate_change_nb);
>  
>  /**
> - * cdns_uart_isr - Interrupt handler
> - * @irq: Irq number
> - * @dev_id: Id of the port
> - *
> - * Return: IRQHANDLED
> + * cdns_uart_handle_tx - Handle the bytes to be Txed.
> + * @dev_id: Id of the UART port
> + * Return: None
>   */
> -static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
> +static void cdns_uart_handle_tx(void *dev_id)
>  {
>  	struct uart_port *port = (struct uart_port *)dev_id;
> -	unsigned long flags;
> -	unsigned int isrstatus, numbytes;
> -	unsigned int data;
> -	char status = TTY_NORMAL;
> +	unsigned int numbytes;
>  
> -	spin_lock_irqsave(&port->lock, flags);
> +	if (uart_circ_empty(&port->state->xmit)) {
> +		writel(CDNS_UART_IXR_TXEMPTY, port->membase +
> +		       CDNS_UART_IDR_OFFSET);
> +	} else {
> +		numbytes = port->fifosize;
> +		/* Break if no more data available in the UART buffer */
> +		while (numbytes--) {
> +			if (uart_circ_empty(&port->state->xmit))
> +				break;
> +			/*
> +			 * Get the data from the UART circular buffer
> +			 * and write it to the cdns_uart's TX_FIFO
> +			 * register.
> +			 */
> +			writel(port->state->xmit.buf[port->state->xmit.tail],
> +			       port->membase + CDNS_UART_FIFO_OFFSET);
>  
> -	/* Read the interrupt status register to determine which
> -	 * interrupt(s) is/are active.
> -	 */
> -	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
> +			port->icount.tx++;
>  
> -	/*
> -	 * There is no hardware break detection, so we interpret framing
> -	 * error with all-zeros data as a break sequence. Most of the time,
> -	 * there's another non-zero byte at the end of the sequence.
> -	 */
> -	if (isrstatus & CDNS_UART_IXR_FRAMING) {
> -		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
> -					CDNS_UART_SR_RXEMPTY)) {
> -			if (!readl(port->membase + CDNS_UART_FIFO_OFFSET)) {
> -				port->read_status_mask |= CDNS_UART_IXR_BRK;
> -				isrstatus &= ~CDNS_UART_IXR_FRAMING;
> -			}
> +			/*
> +			 * Adjust the tail of the UART buffer and wrap
> +			 * the buffer if it reaches limit.
> +			 */
> +			port->state->xmit.tail =
> +				(port->state->xmit.tail + 1) &
> +					(UART_XMIT_SIZE - 1);
>  		}
> -		writel(CDNS_UART_IXR_FRAMING,
> -				port->membase + CDNS_UART_ISR_OFFSET);
> -	}
>  
> -	/* drop byte with parity error if IGNPAR specified */
> -	if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
> -		isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);
> +		if (uart_circ_chars_pending(
> +				&port->state->xmit) < WAKEUP_CHARS)
> +			uart_write_wakeup(port);
> +	}
> +}
>  
> -	isrstatus &= port->read_status_mask;
> -	isrstatus &= ~port->ignore_status_mask;
> +/**
> + * cdns_uart_handle_rx - Handle the received bytes along with Rx errors.
> + * @dev_id: Id of the UART port
> + * @isrstatus: The interrupt status register value as read
> + * Return: None
> + */
> +static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
> +{
> +	struct uart_port *port = (struct uart_port *)dev_id;
> +	unsigned int data;
> +	unsigned int framerrprocessed = 0;
> +	char status = TTY_NORMAL;
>  
> -	if ((isrstatus & CDNS_UART_IXR_TOUT) ||
> -		(isrstatus & CDNS_UART_IXR_RXTRIG)) {
> -		/* Receive Timeout Interrupt */
> -		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
> -					CDNS_UART_SR_RXEMPTY)) {
> -			data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
> +	while ((readl(port->membase + CDNS_UART_SR_OFFSET) &
> +		CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
> +		data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
> +		port->icount.rx++;
> +		/*
> +		 * There is no hardware break detection, so we interpret
> +		 * framing error with all-zeros data as a break sequence.
> +		 * Most of the time, there's another non-zero byte at the
> +		 * end of the sequence.
> +		 */
> +		if (isrstatus & CDNS_UART_IXR_FRAMING) {
> +			if (!data) {
> +				port->read_status_mask |= CDNS_UART_IXR_BRK;
> +				framerrprocessed = 1;
> +				continue;
> +			}
> +		}
> +		isrstatus &= port->read_status_mask;
> +		isrstatus &= ~port->ignore_status_mask;
>  
> -			/* Non-NULL byte after BREAK is garbage (99%) */
> -			if (data && (port->read_status_mask &
> -						CDNS_UART_IXR_BRK)) {
> +		if ((isrstatus & CDNS_UART_IXR_TOUT) ||
> +		    (isrstatus & CDNS_UART_IXR_RXTRIG)) {
> +			if (data &&
> +			    (port->read_status_mask & CDNS_UART_IXR_BRK)) {
>  				port->read_status_mask &= ~CDNS_UART_IXR_BRK;
>  				port->icount.brk++;
>  				if (uart_handle_break(port))
> @@ -249,67 +274,56 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
>  				spin_lock(&port->lock);
>  			}
>  #endif
> -
> -			port->icount.rx++;
> -
>  			if (isrstatus & CDNS_UART_IXR_PARITY) {
>  				port->icount.parity++;
>  				status = TTY_PARITY;
> -			} else if (isrstatus & CDNS_UART_IXR_FRAMING) {
> +			}
> +			if ((isrstatus & CDNS_UART_IXR_FRAMING) &&
> +			    !framerrprocessed) {
>  				port->icount.frame++;
>  				status = TTY_FRAME;
> -			} else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
> +			}
> +			if (isrstatus & CDNS_UART_IXR_OVERRUN) {
>  				port->icount.overrun++;
> +				tty_insert_flip_char(&port->state->port, 0,
> +						     TTY_OVERRUN);
>  			}
> -
> -			uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
> -					data, status);
> +			tty_insert_flip_char(&port->state->port, data, status);
>  		}
> -		spin_unlock(&port->lock);
> -		tty_flip_buffer_push(&port->state->port);
> -		spin_lock(&port->lock);
>  	}
> +	spin_unlock(&port->lock);
> +	tty_flip_buffer_push(&port->state->port);
> +	spin_lock(&port->lock);
> +}
>  
> -	/* Dispatch an appropriate handler */
> -	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
> -		if (uart_circ_empty(&port->state->xmit)) {
> -			writel(CDNS_UART_IXR_TXEMPTY,
> -					port->membase + CDNS_UART_IDR_OFFSET);
> -		} else {
> -			numbytes = port->fifosize;
> -			/* Break if no more data available in the UART buffer */
> -			while (numbytes--) {
> -				if (uart_circ_empty(&port->state->xmit))
> -					break;
> -				/* Get the data from the UART circular buffer
> -				 * and write it to the cdns_uart's TX_FIFO
> -				 * register.
> -				 */
> -				writel(port->state->xmit.buf[
> -						port->state->xmit.tail],
> -					port->membase + CDNS_UART_FIFO_OFFSET);
> -
> -				port->icount.tx++;
> -
> -				/* Adjust the tail of the UART buffer and wrap
> -				 * the buffer if it reaches limit.
> -				 */
> -				port->state->xmit.tail =
> -					(port->state->xmit.tail + 1) &
> -						(UART_XMIT_SIZE - 1);
> -			}
> +/**
> + * cdns_uart_isr - Interrupt handler
> + * @irq: Irq number
> + * @dev_id: Id of the port
> + *
> + * Return: IRQHANDLED
> + */
> +static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
> +{
> +	struct uart_port *port = (struct uart_port *)dev_id;
> +	unsigned int isrstatus;
>  
> -			if (uart_circ_chars_pending(
> -					&port->state->xmit) < WAKEUP_CHARS)
> -				uart_write_wakeup(port);
> -		}
> -	}
> +	spin_lock(&port->lock);
>  
> +	/* Read the interrupt status register to determine which
> +	 * interrupt(s) is/are active and clear them.
> +	 */
> +	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
>  	writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
>  
> -	/* be sure to release the lock and tty before leaving */
> -	spin_unlock_irqrestore(&port->lock, flags);
> +	if (isrstatus & CDNS_UART_IXR_TXEMPTY) {
> +		cdns_uart_handle_tx(dev_id);
> +		isrstatus &= ~CDNS_UART_IXR_TXEMPTY;
> +	}
> +	if (isrstatus & CDNS_UART_IXR_MASK)
> +		cdns_uart_handle_rx(dev_id, isrstatus);
>  
> +	spin_unlock(&port->lock);
>  	return IRQ_HANDLED;
>  }
>  
> 

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#1208789 — Re: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic

FromPeter Hurley <peter@hurleysoftware.com>
Date2015-08-17 20:50 +0200
SubjectRe: [PATCH 4/4] serial: xuartps: Rewrite the interrupt handling logic
Message-ID<pYxDP-7fc-5@gated-at.bofh.it>
In reply to#1208670
On 08/17/2015 12:00 PM, Anirudha Sarangi wrote:
>> From: Peter Hurley [mailto:peter@hurleysoftware.com]
>> On 08/17/2015 03:22 AM, Michal Simek wrote:
>>> From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>
>>>
>>> The existing interrupt handling logic has followins issues.
>>> - Upon a parity error with default configuration, the control
>>>   never comes out of the ISR thereby hanging Linux.
>>> - The error handling logic around framing and parity error are buggy.
>>>   There are chances that the errors will never be captured.
>>> - The existing ISR is just too long.
>>> This patch fixes all these concerns.
>>
>> This patch is unreviewable. Please break this down into multiple patches.
>>
> Thanks. Let me give a shot. It is just breaking the single big ISR that has both Rx and Tx in a single function into smaller ones.
> Not sure how I will create smaller patches, but I will try and get back.

I would start with a refactor patch that splits up the ISR but
makes no other functional changes. Then add the bug fix patches.

Regards,
Peter Hurley

ps - The email signature below is not appropriate for lkml.

> 
> This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.
> 

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#1208651 — Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity

FromPeter Hurley <peter@hurleysoftware.com>
Date2015-08-17 17:40 +0200
SubjectRe: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity
Message-ID<pYuFY-30K-21@gated-at.bofh.it>
In reply to#1208424
On 08/17/2015 03:22 AM, Michal Simek wrote:
> From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>
> 
> Existing set_termios does not handle the option for enabling
> odd parity. This patch fixes it.

NAK. PARODD does not enable parity generation or detection.

Regards,
Peter Hurley

> Signed-off-by: Anirudha Sarangi <anirudh@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> ---
> 
>  drivers/tty/serial/xilinx_uartps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
> index 009e0dbc12d2..a3020344ac9d 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -723,7 +723,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
>  	else
>  		cval |= CDNS_UART_MR_STOPMODE_1_BIT; /* 1 STOP bit */
>  
> -	if (termios->c_cflag & PARENB) {
> +	if ((termios->c_cflag & PARENB) || (termios->c_cflag & PARODD)) {
>  		/* Mark or Space parity */
>  		if (termios->c_cflag & CMSPAR) {
>  			if (termios->c_cflag & PARODD)
> 

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#1208699 — Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity

FromPeter Hurley <peter@hurleysoftware.com>
Date2015-08-17 18:30 +0200
SubjectRe: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity
Message-ID<pYvsm-4bw-13@gated-at.bofh.it>
In reply to#1208651
On 08/17/2015 11:55 AM, Anirudha Sarangi wrote:
> Hi,
> 
>> -----Original Message-----
>> From: Peter Hurley [mailto:peter@hurleysoftware.com]
>> Sent: Monday, August 17, 2015 9:09 PM
>> To: Michal Simek
>> Cc: linux-kernel@vger.kernel.org; monstr@monstr.eu; Anirudha Sarangi; Soren
>> Brinkmann; Jiri Slaby; linux-serial@vger.kernel.org; Greg Kroah-Hartman; linux-
>> arm-kernel@lists.infradead.org
>> Subject: Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity
>>
>> On 08/17/2015 03:22 AM, Michal Simek wrote:
>>> From: Anirudha Sarangi <anirudha.sarangi@xilinx.com>
>>>
>>> Existing set_termios does not handle the option for enabling odd
>>> parity. This patch fixes it.
>>
>> NAK. PARODD does not enable parity generation or detection.
>>
> What if someone is trying to change from even to odd parity?

If userspace wants odd parity, then c_cflag must have both
PARENB and PARODD set.

Just PARODD does nothing.

From SUS v4, General Terminal Interface, 11.2.4 Control Modes;

"If PARENB is set, parity generation and detection shall be enabled
and a parity bit is added to each byte. If parity is enabled, PARODD
shall specify odd parity if set; otherwise, even parity shall be used."



> In this conditional case, we setup some register bit for the same.
> Is the above use case not a valid one?
> 
> Regards
> Anirudha
> 
>> Regards,
>> Peter Hurley
>>
>>> Signed-off-by: Anirudha Sarangi <anirudh@xilinx.com>
>>> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
>>> ---
>>>
>>>  drivers/tty/serial/xilinx_uartps.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/tty/serial/xilinx_uartps.c
>>> b/drivers/tty/serial/xilinx_uartps.c
>>> index 009e0dbc12d2..a3020344ac9d 100644
>>> --- a/drivers/tty/serial/xilinx_uartps.c
>>> +++ b/drivers/tty/serial/xilinx_uartps.c
>>> @@ -723,7 +723,7 @@ static void cdns_uart_set_termios(struct uart_port
>> *port,
>>>     else
>>>             cval |= CDNS_UART_MR_STOPMODE_1_BIT; /* 1 STOP bit */
>>>
>>> -   if (termios->c_cflag & PARENB) {
>>> +   if ((termios->c_cflag & PARENB) || (termios->c_cflag & PARODD)) {
>>>             /* Mark or Space parity */
>>>             if (termios->c_cflag & CMSPAR) {
>>>                     if (termios->c_cflag & PARODD)
>>>
> 
> 
> 
> This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.
> 

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