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

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Date:   Fri, 08 Jul 2022 10:07:08 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     todd.e.brandt@...ux.intel.com, 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)

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