linux-kernel - Re: PNP0501 serial driver takes almost 2 seconds to suspend/resume (printk issue)

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Message-ID: <CAHp75VfyzMNMO2NRwXwSjAmQqBbdRG3+SzyFDG+90dmvmg1xLQ@mail.gmail.com>
Date:   Sun, 10 Jul 2022 21:39:07 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     todd.e.brandt@...ux.intel.com, Petr Mladek <pmladek@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: PNP0501 serial driver takes almost 2 seconds to suspend/resume
 (printk issue)

On Sat, Jul 9, 2022 at 10:48 PM John Ogness <john.ogness@...utronix.de> wrote:
>
> On 2022-07-08, Todd Brandt <todd.e.brandt@...ux.intel.com> wrote:
> > The dmesg logs are in the html timelines themselves, just click the
> > "dmesg" button in the upper right hand corner. The log button shows
> > all kinds of system info as well.
>
> Since the beginning of the kernel log is missing, I still do not see
> information about which serial driver you are using. But since it is
> x86, I'll assume it is an 8250.
>
> Looking at freeze-5.19.0-rc1-bad.html, at 3431.221039 we see that
> suspend_console() was called. The additional 1-second delay you are
> referring to would be 3432.436187, where serial is suspended. pr_flush()
> would have been satisfied when the message at 3431.221039 was
> printed. So the question is, why is there still printing going on?

It might be no_console_suspend hack. Are you, btw, aware of this ugly
hack in the kernel?

-- 
With Best Regards,
Andy Shevchenko