serial: core: Call device_set_awake_path() for console port

In case the UART port is used as a console, no_console_suspend is
available in bootargs and UART port is part of a software-controlled power
domain we need to call device_set_awake_path(). This lets the power
domain core code know that this domain should not be powered off
during system suspend. Otherwise, the UART port power domain is turned off,
nothing is printed while suspending and the suspend/resume process is
blocked. This was detected on the Renesas RZ/G3S SoC while adding support
for power domains.

Based on code investigation (on v6.9-rc5), this issue is present on other
SoCs (e.g., Renesas R-Mobile A1 [1], IMX8QXP [2]) and different SoCs have
particular implementation to handle it. Due to this the patch added the
call of device_set_awake_path() in uart_suspend_port() instead of having
it in the platform specific UART driver.

[1] drivers/pmdomain/renesas/rmobile-sysc.c:116
[2] drivers/pmdomain/imx/scu-pd.c:357

Suggested-by: Ulf Hansson <ulf.hansson@linaro.org>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240430095930.2806067-1-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 8a76f378c44570fffb42d1ce601d23a7fe4ac792..84ae70d52b056aeeeb182c967e3a5dc7881c3b94 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2408,6 +2408,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
                        uport->ops->stop_rx(uport);
                        uart_port_unlock_irq(uport);
                }
+               device_set_awake_path(uport->dev);
                goto unlock;
        }