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SubjectRe: UART/TTY console deadlock
* Sergey Senozhatsky <sergey.senozhatsky@gmail.com> [200702 05:13]:
> On (20/06/30 11:02), Tony Lindgren wrote:
> > This conditional disable for irq_shared does not look nice to me
> > from the other device point of view :)
> >
> > Would it be possible to just set up te dummy interrupt handler
> > for the startup, then change it back afterwards? See for example
> > omap8250_no_handle_irq().
>
> I think we can do it. serial8250_do_startup() and irq handler take
> port->lock, so they should be synchronized.
>
> Something like this then?

Yeah thanks this should work better for shared irq.

Regards,

Tony

> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index f77bf820b7a3..61ad6f5f0f88 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2140,6 +2140,11 @@ static void serial8250_put_poll_char(struct uart_port *port,
>
> #endif /* CONFIG_CONSOLE_POLL */
>
> +static int serial8250_dummy_handle_irq(struct uart_port *port)
> +{
> + return 0;
> +}
> +
> int serial8250_do_startup(struct uart_port *port)
> {
> struct uart_8250_port *up = up_to_u8250p(port);
> @@ -2271,6 +2276,9 @@ int serial8250_do_startup(struct uart_port *port)
>
> if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
> unsigned char iir1;
> + int (*handler)(struct uart_port *);
> +
> + handler = port->handle_irq;
> /*
> * Test for UARTs that do not reassert THRE when the
> * transmitter is idle and the interrupt has already
> @@ -2280,8 +2288,7 @@ int serial8250_do_startup(struct uart_port *port)
> * allow register changes to become visible.
> */
> spin_lock_irqsave(&port->lock, flags);
> - if (up->port.irqflags & IRQF_SHARED)
> - disable_irq_nosync(port->irq);
> + port->handle_irq = serial8250_dummy_handle_irq;
>
> wait_for_xmitr(up, UART_LSR_THRE);
> serial_port_out_sync(port, UART_IER, UART_IER_THRI);
> @@ -2293,8 +2300,7 @@ int serial8250_do_startup(struct uart_port *port)
> iir = serial_port_in(port, UART_IIR);
> serial_port_out(port, UART_IER, 0);
>
> - if (port->irqflags & IRQF_SHARED)
> - enable_irq(port->irq);
> + port->handle_irq = handler;
> spin_unlock_irqrestore(&port->lock, flags);
>
> /*

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