| Message ID | 1448161172-19717-10-git-send-email-soren.brinkmann@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/21/2015 09:59 PM, Soren Brinkmann wrote: > Ignore RX-related interrupts if RX is not enabled. This doesn't look like a safe approach; fast-forward a couple of years and some is trying to add some feature but can't figure out why no data is arriving... What is this trying to solve? Regards, Peter Hurley > Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> > --- > drivers/tty/serial/xilinx_uartps.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c > index db9e23eaf300..3a1e508926c1 100644 > --- a/drivers/tty/serial/xilinx_uartps.c > +++ b/drivers/tty/serial/xilinx_uartps.c > @@ -161,6 +161,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255"); > * @pclk: APB clock > * @baud: Current baud rate > * @clk_rate_change_nb: Notifier block for clock changes > + * @flags: Driver flags > */ > struct cdns_uart { > struct uart_port *port; > @@ -168,7 +169,11 @@ struct cdns_uart { > struct clk *pclk; > unsigned int baud; > struct notifier_block clk_rate_change_nb; > + u32 flags; > }; > + > +#define CDNS_FLAG_RX_ENABLED BIT(0) > + > #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ > clk_rate_change_nb); > > @@ -262,6 +267,7 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus) > static irqreturn_t cdns_uart_isr(int irq, void *dev_id) > { > struct uart_port *port = (struct uart_port *)dev_id; > + struct cdns_uart *cdns_uart = port->private_data; > unsigned long flags; > unsigned int isrstatus, numbytes; > > @@ -272,7 +278,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id) > */ > isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET); > > - cdns_uart_handle_rx(port, isrstatus); > + if (cdns_uart->flags & CDNS_FLAG_RX_ENABLED) > + cdns_uart_handle_rx(port, isrstatus); > > /* Dispatch an appropriate handler */ > if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) { > @@ -579,11 +586,13 @@ static void cdns_uart_stop_tx(struct uart_port *port) > static void cdns_uart_stop_rx(struct uart_port *port) > { > unsigned int regval; > + struct cdns_uart *cdns_uart = port->private_data; > > regval = readl(port->membase + CDNS_UART_CR_OFFSET); > regval |= CDNS_UART_CR_RX_DIS; > /* Disable the receiver */ > writel(regval, port->membase + CDNS_UART_CR_OFFSET); > + cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED; > } > > /** > @@ -764,6 +773,7 @@ static int cdns_uart_startup(struct uart_port *port) > { > unsigned long flags; > unsigned int retval = 0, status = 0; > + struct cdns_uart *cdns_uart = port->private_data; > > retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, > (void *)port); > @@ -790,6 +800,7 @@ static int cdns_uart_startup(struct uart_port *port) > status &= CDNS_UART_CR_RX_DIS; > status |= CDNS_UART_CR_RX_EN; > writel(status, port->membase + CDNS_UART_CR_OFFSET); > + cdns_uart->flags |= CDNS_FLAG_RX_ENABLED; > > /* Set the Mode Register with normal mode,8 data bits,1 stop bit, > * no parity. > @@ -833,6 +844,7 @@ static void cdns_uart_shutdown(struct uart_port *port) > { > int status; > unsigned long flags; > + struct cdns_uart *cdns_uart = port->private_data; > > spin_lock_irqsave(&port->lock, flags); > > @@ -844,6 +856,7 @@ static void cdns_uart_shutdown(struct uart_port *port) > /* Disable the TX and RX */ > writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS, > port->membase + CDNS_UART_CR_OFFSET); > + cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED; > > spin_unlock_irqrestore(&port->lock, flags); > >
On Sat, 2015-12-05 at 12:43PM -0500, Peter Hurley wrote: > On 11/21/2015 09:59 PM, Soren Brinkmann wrote: > > Ignore RX-related interrupts if RX is not enabled. > > This doesn't look like a safe approach; fast-forward a couple of years and > some is trying to add some feature but can't figure out why no data is > arriving... > > What is this trying to solve? I definitely saw two kinds of lock ups. One was on the TX side, that the system tried to print with the transmitter disabled. The other on the RX side. I don't recall the details, but the system was stuck in some RX-related function waiting for data while the receiver was disabled. I think my explanation was that some IRQ condition becomes true and is dispatched to the RX handler even though the receiver isn't enabled. I guess a better way for solving this would be to disable the IRQs that call the RX handler when the receiver is disabled. Sören
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index db9e23eaf300..3a1e508926c1 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -161,6 +161,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255"); * @pclk: APB clock * @baud: Current baud rate * @clk_rate_change_nb: Notifier block for clock changes + * @flags: Driver flags */ struct cdns_uart { struct uart_port *port; @@ -168,7 +169,11 @@ struct cdns_uart { struct clk *pclk; unsigned int baud; struct notifier_block clk_rate_change_nb; + u32 flags; }; + +#define CDNS_FLAG_RX_ENABLED BIT(0) + #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ clk_rate_change_nb); @@ -262,6 +267,7 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus) static irqreturn_t cdns_uart_isr(int irq, void *dev_id) { struct uart_port *port = (struct uart_port *)dev_id; + struct cdns_uart *cdns_uart = port->private_data; unsigned long flags; unsigned int isrstatus, numbytes; @@ -272,7 +278,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id) */ isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET); - cdns_uart_handle_rx(port, isrstatus); + if (cdns_uart->flags & CDNS_FLAG_RX_ENABLED) + cdns_uart_handle_rx(port, isrstatus); /* Dispatch an appropriate handler */ if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) { @@ -579,11 +586,13 @@ static void cdns_uart_stop_tx(struct uart_port *port) static void cdns_uart_stop_rx(struct uart_port *port) { unsigned int regval; + struct cdns_uart *cdns_uart = port->private_data; regval = readl(port->membase + CDNS_UART_CR_OFFSET); regval |= CDNS_UART_CR_RX_DIS; /* Disable the receiver */ writel(regval, port->membase + CDNS_UART_CR_OFFSET); + cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED; } /** @@ -764,6 +773,7 @@ static int cdns_uart_startup(struct uart_port *port) { unsigned long flags; unsigned int retval = 0, status = 0; + struct cdns_uart *cdns_uart = port->private_data; retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, (void *)port); @@ -790,6 +800,7 @@ static int cdns_uart_startup(struct uart_port *port) status &= CDNS_UART_CR_RX_DIS; status |= CDNS_UART_CR_RX_EN; writel(status, port->membase + CDNS_UART_CR_OFFSET); + cdns_uart->flags |= CDNS_FLAG_RX_ENABLED; /* Set the Mode Register with normal mode,8 data bits,1 stop bit, * no parity. @@ -833,6 +844,7 @@ static void cdns_uart_shutdown(struct uart_port *port) { int status; unsigned long flags; + struct cdns_uart *cdns_uart = port->private_data; spin_lock_irqsave(&port->lock, flags); @@ -844,6 +856,7 @@ static void cdns_uart_shutdown(struct uart_port *port) /* Disable the TX and RX */ writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS, port->membase + CDNS_UART_CR_OFFSET); + cdns_uart->flags &= ~CDNS_FLAG_RX_ENABLED; spin_unlock_irqrestore(&port->lock, flags);
Ignore RX-related interrupts if RX is not enabled. Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> --- drivers/tty/serial/xilinx_uartps.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)