Messages in this thread | | | Date | Thu, 2 Jul 2020 09:05:14 -0700 | From | Tony Lindgren <> | Subject | Re: UART/TTY console deadlock |
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* 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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