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tty: serial: fsl_lpuart: mark last busy before uart_add_one_port

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commit dc98d76a15 upstream.

With "earlycon initcall_debug=1 loglevel=8" 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.

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);

So in the end, before normal console ready, the lpuart get runtime
suspended. And earlycon putchar will hang.

To address the issue, mark last busy just after pm_runtime_enable,
three seconds is long enough to switch from bootconsole to normal
console.

Fixes: 43543e6f53 ("tty: serial: fsl_lpuart: Add runtime pm support")
Cc: stable <stable@kernel.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20240808140325.580105-1-peng.fan@oss.nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peng Fan 2024-08-08 22:03:25 +08:00 committed by Greg Kroah-Hartman
parent 4c1a2d4cd9
commit 8eb92cfca6
1 changed files with 1 additions and 0 deletions
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1
drivers/tty/serial/fsl_lpuart.c
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@ -2930,6 +2930,7 @@ static int lpuart_probe(struct platform_device *pdev)
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);
ret = lpuart_global_reset(sport);
if (ret)