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

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Message-ID: <045ebee30af2b80aaeace1dab18ecd113e3f17c7.camel@linux.intel.com>
Date:   Fri, 08 Jul 2022 14:35:59 -0700
From:   Todd Brandt <todd.e.brandt@...ux.intel.com>
To:     John Ogness <john.ogness@...utronix.de>, pmladek@...e.com
Cc:     linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        senozhatsky@...omium.org, rostedt@...dmis.org
Subject: Re: PNP0501 serial driver takes almost 2 seconds to suspend/resume
 (printk issue)

On Fri, 2022-07-08 at 10:07 +0206, John Ogness wrote:
> Hi Todd,
> 
> Thanks for reporting this.
> 
> On 2022-07-07, Todd Brandt <todd.e.brandt@...ux.intel.com> wrote:
> > Ever since 5.19.0-rc1 the serial device has taken almost a second
> > longer in both suspend and resume. This effect is witnessed in half
> > the machines in our lab (~10 machines). It occurs on dell, asus,
> > gigabyte and other machines so it's not hardware specific.
> 
> Please provide a full dmesg log if you can. The important parts of
> the
> log would be:
> 
> - boot arguments
> - any lines with "printk" in it
> - timing information
> - messages during suspend and resume
> 
> pr_flush() uses a timeout of 1 second. I assume your console driver
> is
> not printing and therefore not making any forward progress.
> 
> John Ogness

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.