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 <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
