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

Todd Brandt
2022-07-07T20:45:27Z

Adding printk maintainers to the thread

On Thu, 2022-07-07 at 13:31 -0700, Todd Brandt 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.
>
> I opened a bugzilla issue which includes the git bisect:
> https://bugzilla.kernel.org/show_bug.cgi?id=216216
>
>
> Bad commit:
>
> commit 3b604ca81202eea2a917eb6491e90f610fba0ec7
> Author: John Ogness <john.ogness@linutronix.de>
> Date: Thu Apr 21 23:28:46 2022 +0206
>
> printk: add pr_flush()
>
> Provide a might-sleep function to allow waiting for console
> printers
> to catch up to the latest logged message.
>
> Use pr_flush() whenever it is desirable to get buffered messages
> printed before continuing: suspend_console(), resume_console(),
> console_stop(), console_start(), console_unblank().
>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
> Link:
>
https://lore.kernel.org/r/20220421212250.565456-12-john.ogness@linutronix.de
>
> include/linux/printk.h | 7 +++++
> kernel/printk/printk.c | 83
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 90 insertions(+)