From: Kurt Kanzenbach <kurt@linutronix.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: 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, 06 Jul 2020 13:31:01 +0200 [thread overview]
Message-ID: <877dvg6ft6.fsf@kurt> (raw)
In-Reply-To: <CAHp75VdvNi_LWv7QhEsm1vQikeiMpi68qmCwoVttjnp7oq0ahg@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2735 bytes --]
Hi,
On Sat Jul 04 2020, Andy Shevchenko wrote:
> On Fri, Jul 3, 2020 at 1:32 PM Sergey Senozhatsky
> <sergey.senozhatsky@gmail.com> wrote:
>>
>> On (20/07/02 09:05), Tony Lindgren wrote:
>> > * 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.
>>
>> This is, basically, an equivalent of
>>
>> ---
>> drivers/tty/serial/8250/8250_port.c | 5 +----
>> 1 file changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
>> index d64ca77d9cfa..dba7747d2ddd 100644
>> --- a/drivers/tty/serial/8250/8250_port.c
>> +++ b/drivers/tty/serial/8250/8250_port.c
>> @@ -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.
Thanks,
Kurt
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]
next prev parent reply other threads:[~2020-07-06 11:31 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 [this message]
2020-07-06 14:43 ` Sergey Senozhatsky
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=877dvg6ft6.fsf@kurt \
--to=kurt@linutronix.de \
--cc=Shirish.S@amd.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=andy.shevchenko@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=john.ogness@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=rostedt@goodmis.org \
--cc=rrangel@google.com \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=sergey.senozhatsky@gmail.com \
--cc=tony@atomide.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).