On 12/05/2015 08:39 PM, Soren Brinkmann wrote:
> Request_irq() should be _after_ h/w programming, otherwise an
> interrupt could be triggered and in-progress before the h/w has been
> setup.
Slight misunderstanding. My fault; I should have been more explicit.
1. Any setup necessary for the isr not to be confused and misdirect spurious
interrupts (or hang) should be before installing the isr with request_irq()
None of this code should trigger an interrupt.
2. Clear pending interrupts
3. Install the isr with request_irq()
4. Enable interrupts
For extra safety, first disable interrupts before starting h/w programming.
I would do the v5 series in the same order as the v3 series only up to
what I reviewed. Then do another series with the remainder plus new changes, ok?
Regards,
Peter Hurley
> Reported-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
> ---
> v4:
> - this patch has been added. Thanks to Peter for pointing it out and providing
> commit message
> ---
> drivers/tty/serial/xilinx_uartps.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
> index 6ffd3bbe3e18..1e9053656610 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -759,12 +759,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
> static int cdns_uart_startup(struct uart_port *port)
> {
> unsigned long flags;
> - unsigned int retval = 0, status = 0;
> -
> - retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
> - (void *)port);
> - if (retval)
> - return retval;
> + unsigned int status = 0;
>
> spin_lock_irqsave(&port->lock, flags);
>
> @@ -818,7 +813,7 @@ static int cdns_uart_startup(struct uart_port *port)
>
> spin_unlock_irqrestore(&port->lock, flags);
>
> - return retval;
> + return request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, port);
> }
>
> /**
>
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