On Thu, Sep 14, 2023 at 06:26:44PM +0200, Thomas Richard wrote:
> Hi
>
> After switching to Linux 6.6-rc1, i met an issue during suspend to idle
> with 8250_omap driver (no_console_suspend is set).
> The driver fails to suspend the uart port used for the serial console so
> the suspend sequence is stopped.
>
> [ 114.629197] port 2800000.serial:0.0: PM: calling
> pm_runtime_force_suspend+0x0/0x134 @ 114, parent: 2800000.serial:0
> [ 114.639617] port 2800000.serial:0.0: PM:
> pm_runtime_force_suspend+0x0/0x134 returned 0 after 2 usecs
> [ 114.648739] omap8250 2800000.serial: PM: calling
> omap8250_suspend+0x0/0xf4 @ 114, parent: bus@100000
> [ 114.657861] omap8250 2800000.serial: PM: dpm_run_callback():
> omap8250_suspend+0x0/0xf4 returns -16
> [ 114.666808] omap8250 2800000.serial: PM: omap8250_suspend+0x0/0xf4
> returned -16 after 8951 usecs
> [ 114.675580] omap8250 2800000.serial: PM: failed to suspend: error -16
> [ 114.682011] PM: suspend of devices aborted after 675.644 msecs
> [ 114.687833] PM: start suspend of devices aborted after 681.777 msecs
> [ 114.694175] PM: Some devices failed to suspend, or early wake event
> detected
>
> The following sequence is used to suspend to idle:
> $ echo 1 > /sys/power/pm_debug_messages
> $ echo 1 > /sys/power/pm_print_times
> $ echo 8 > /proc/sys/kernel/printk
> $ echo 0 > /sys/module/printk/parameters/console_suspend
> $ echo enabled >
> /sys/devices/platform/bus@100000/2800000.serial/tty/ttyS2/power/wakeup
> $ echo s2idle > /sys/power/mem_sleep
> $ echo mem > /sys/power/state
>
> The regression was introduced in commit 20a41a62618d "serial: 8250_omap:
> Use force_suspend and resume for system suspend"
>
> Before commit 20a41a62618d, omap8250_suspend returned 0.
> Now pm_runtime_force_suspend is called and its return code is used by
> omap8250_suspend.
>
> static int omap8250_suspend(struct device *dev)
> {
> struct omap8250_priv *priv = dev_get_drvdata(dev);
> struct uart_8250_port *up = serial8250_get_port(priv->line);
> int err;
>
> serial8250_suspend_port(priv->line);
>
> err = pm_runtime_resume_and_get(dev);
> if (err)
> return err;
> if (!device_may_wakeup(dev))
> priv->wer = 0;
> serial_out(up, UART_OMAP_WER, priv->wer);
> err = pm_runtime_force_suspend(dev);
> flush_work(&priv->qos_work);
>
> return err;
> }
>
> The pm_runtime_force_suspend function calls omap8250_runtime_suspend
> which returns -EBUSY because console suspend was disabled (which is my
> case), as explained in the code.
>
> /*
> * When using 'no_console_suspend', the console UART must not be
> * suspended. Since driver suspend is managed by runtime suspend,
> * preventing runtime suspend (by returning error) will keep device
> * active during suspend.
> */
> if (priv->is_suspending && !console_suspend_enabled) {
> if (up && uart_console(&up->port))
> return -EBUSY;
> }
>
> The port is used by the console, so we don't want to suspend it (console
> suspend was disabled).
> Of course, if console_suspend is enabled and messages are disabled there
> is no issue.
Do you have a proposed patch to fix this? Or should the original be
reverted?
thanks,
greg k-h
