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August 2024, 16:03:25 CEST schrieb Peng Fan (OSS): > From: Peng Fan >=20 > With "earlycon initcall_debug=3D1 loglevel=3D8" in bootargs, kernel > sometimes boot hang. It is because normal console still is not ready, > but runtime suspend is called, so early console putchar will hang > in waiting TRDE set in UARTSTAT. >=20 > The lpuart driver has auto suspend delay set to 3000ms, but during > uart_add_one_port, a child device serial ctrl will added and probed with > its pm runtime enabled(see serial_ctrl.c). > The runtime suspend call path is: > device_add > |-> bus_probe_device > |->device_initial_probe > |->__device_attach > |-> pm_runtime_get_sync(dev->parent); > |-> pm_request_idle(dev); > |-> pm_runtime_put(dev->parent); >=20 > So in the end, before normal console ready, the lpuart get runtime > suspended. And earlycon putchar will hang. >=20 > To address the issue, mark last busy just after pm_runtime_enable, > three seconds is long enough to switch from bootconsole to normal > console. >=20 > Fixes: 43543e6f539b ("tty: serial: fsl_lpuart: Add runtime pm support") > Signed-off-by: Peng Fan > --- > drivers/tty/serial/fsl_lpuart.c | 1 + > 1 file changed, 1 insertion(+) >=20 > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpu= art.c > index 615291ea9b5e..77efa7ee6eda 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -2923,6 +2923,7 @@ static int lpuart_probe(struct platform_device *pde= v) > pm_runtime_set_autosuspend_delay(&pdev->dev, UART_AUTOSUSPEND_TIMEOUT); > pm_runtime_set_active(&pdev->dev); > pm_runtime_enable(&pdev->dev); > + pm_runtime_mark_last_busy(&pdev->dev); This change looks sensible to me. Is maybe [1] addressing the same issue at= a different level? Best regards, Alexander [1] https://lore.kernel.org/all/20240808-gs101-non-essential-clocks-2-v6-0-= e91c537acedc@linaro.org/ > =20 > ret =3D lpuart_global_reset(sport); > if (ret) >=20 =2D-=20 TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/