Messages in this thread | | | Date | Tue, 30 Jun 2020 11:02:55 -0700 | From | Tony Lindgren <> | Subject | Re: UART/TTY console deadlock |
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* Sergey Senozhatsky <sergey.senozhatsky@gmail.com> [200630 13:06]: > On (20/06/30 14:22), Petr Mladek wrote: ...
> > > > > @@ -2284,8 +2289,6 @@ 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); > > > > > > > > > > wait_for_xmitr(up, UART_LSR_THRE); > > > > > serial_port_out_sync(port, UART_IER, UART_IER_THRI); > > > > > @@ -2297,9 +2300,9 @@ 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); > > > > > spin_unlock_irqrestore(&port->lock, flags); > > > > > + if (irq_shared) > > > > > + enable_irq(port->irq); > > > > > > > > > > /* > > > > > * If the interrupt is not reasserted, or we otherwise > > > > > > > > I think that it might be safe but I am not 100% sure, sigh. > > > > > > Yeah, I'm not 100%, but I'd give it a try. > > > > I do not feel brave enough to ack it today. But I am all for trying it > > if anyone more familiar with the code is fine with it. > > I see. Well, I suppose we need Ack-s from tty/serial/8250 maintainers. > I would not be very happy if _only_ printk people Ack the patch.
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().
The other device for irq_shared should be capable of dealing with spurious interrupts if it's shared.
Regards,
Tony
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