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Message-ID: <1448026478-22131-2-git-send-email-navam@xilinx.com>
Date: Fri, 20 Nov 2015 19:04:37 +0530
From: Nava kishore Manne <nava.manne@...inx.com>
To: <jslaby@...e.com>, <michal.simek@...inx.com>,
<soren.brinkmann@...inx.com>, <anirudh@...inx.com>
CC: <linux-serial@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
Nava kishore Manne <navam@...inx.com>
Subject: [PATCH v2 2/3] serial: xuartps: Rewrite the interrupt handling logic
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.
This patch fixes all these concerns.
Signed-off-by: Nava kishore Manne <navam@...inx.com>
---
Changes for v2:
--Add required changes after spliting the ISR as suggested by
Peter Hurley.
drivers/tty/serial/xilinx_uartps.c | 64 ++++++++++++++++++--------------------
1 file changed, 31 insertions(+), 33 deletions(-)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2e1b0a8..4d71478 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -191,9 +191,10 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
spin_lock_irqsave(&port->lock, flags);
/* Read the interrupt status register to determine which
- * interrupt(s) is/are active.
+ * interrupt(s) is/are active and clear them.
*/
isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
+ writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
if (isrstatus & CDNS_UART_IXR_TXEMPTY) {
cdns_uart_handle_tx(dev_id);
@@ -202,8 +203,6 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
if (isrstatus & CDNS_UART_IXR_MASK)
cdns_uart_handle_rx(dev_id, isrstatus);
- writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
-
/* be sure to release the lock and tty before leaving */
spin_unlock_irqrestore(&port->lock, flags);
@@ -354,37 +353,32 @@ 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;
- /*
- * 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)) {
+ 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;
- isrstatus &= ~CDNS_UART_IXR_FRAMING;
+ framerrprocessed = 1;
+ continue;
}
}
- 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);
-
- isrstatus &= port->read_status_mask;
- isrstatus &= ~port->ignore_status_mask;
- 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) != CDNS_UART_SR_RXEMPTY) {
- data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+ isrstatus &= port->read_status_mask;
+ isrstatus &= ~port->ignore_status_mask;
+ if ((isrstatus & CDNS_UART_IXR_TOUT) ||
+ (isrstatus & CDNS_UART_IXR_RXTRIG)) {
/* Non-NULL byte after BREAK is garbage (99%) */
if (data && (port->read_status_mask
@@ -416,21 +410,25 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
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) {
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);
}
-}
+
#ifdef CONFIG_COMMON_CLK
/**
* cdns_uart_clk_notitifer_cb - Clock notifier callback
--
2.1.2
--
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