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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Tony Lindgren <tony@atomide.com>, Petr Mladek <pmladek@suse.com>,
	Raul Rangel <rrangel@google.com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	"S, Shirish" <Shirish.S@amd.com>,
	Peter Zijlstra <peterz@infradead.org>,
	John Ogness <john.ogness@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: UART/TTY console deadlock
Date: Mon, 6 Jul 2020 23:43:14 +0900	[thread overview]
Message-ID: <20200706144314.GB1485@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <877dvg6ft6.fsf@kurt>

On (20/07/06 13:31), Kurt Kanzenbach wrote:
> >> @@ -2275,6 +2275,7 @@ int serial8250_do_startup(struct uart_port *port)
> >>
> >>         if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
> >>                 unsigned char iir1;
> >> +
> >>                 /*
> >>                  * Test for UARTs that do not reassert THRE when the
> >>                  * transmitter is idle and the interrupt has already
> >> @@ -2284,8 +2285,6 @@ 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);
> >> @@ -2297,8 +2296,6 @@ 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);
> >>
> >>                 /*
> >
> > ...which effectively is a revert of
> >
> > 768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and
> > RT kernels")
> 
> Please, don't revert that commit. I've faced the same issue as described
> in the commit log. There is hardware available with shared UART
> interrupt lines.

Will this patch break that hardware?
https://lore.kernel.org/lkml/20200702051213.GB3450@jagdpanzerIV.localdomain/

	-ss

  reply	other threads:[~2020-07-06 14:43 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-22 17:30 UART/TTY console deadlock Raul Rangel
2020-06-22 17:37 ` Andy Shevchenko
2020-06-30  3:58   ` Sergey Senozhatsky
2020-06-30 10:21     ` Petr Mladek
2020-06-30 10:55       ` Sergey Senozhatsky
2020-06-30 11:40         ` Andy Shevchenko
2020-06-30 12:22         ` Petr Mladek
2020-06-30 13:05           ` Sergey Senozhatsky
2020-06-30 18:02             ` Tony Lindgren
2020-07-01  6:44               ` S, Shirish
2020-07-02  3:48                 ` S, Shirish
2020-07-02  6:11                   ` Greg Kroah-Hartman
2020-07-02  6:14                     ` S, Shirish
2020-07-02  6:34                       ` Sergey Senozhatsky
2020-07-02  7:11                       ` Greg Kroah-Hartman
2020-07-02  5:12               ` Sergey Senozhatsky
2020-07-02  5:40                 ` Sergey Senozhatsky
2020-07-02  8:20                   ` Andy Shevchenko
2020-07-03 10:53                     ` Sergey Senozhatsky
2020-07-04 11:37                       ` Andy Shevchenko
2020-07-02 16:05                 ` Tony Lindgren
2020-07-03 10:32                   ` Sergey Senozhatsky
2020-07-04 11:35                     ` Andy Shevchenko
2020-07-04 11:59                       ` Andy Shevchenko
2020-07-06 11:31                       ` Kurt Kanzenbach
2020-07-06 14:43                         ` Sergey Senozhatsky [this message]
2020-07-08  7:40                           ` Kurt Kanzenbach
2020-07-08  8:07                             ` Sergey Senozhatsky
2020-07-08  9:52                               ` Petr Mladek
2020-07-09 13:22                                 ` Sergey Senozhatsky
2020-07-14 16:16                                   ` Raul Rangel

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