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serial: qcom-geni: add force suspend/resume to system sleep callbacks

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During system sleep the hardware resources (clocks, interconnect) are
not gated because the runtime-suspend callback is never invoked from
the system sleep path.  This prevents the platform from reaching its
lowest idle state.

The system sleep callbacks qcom_geni_serial_suspend() and
qcom_geni_serial_resume() rely solely on uart_suspend_port() /
uart_resume_port() to manage power.  uart_suspend_port() drives the
UART PM state machine to UART_PM_STATE_OFF, which in turn calls
pm_runtime_put_sync() and eventually the runtime-suspend callback.
However, if the runtime-PM usage count is still elevated at the time
of system sleep (e.g. the port is held active by an open file
descriptor), the runtime-suspend callback is never invoked and the
hardware resources (clocks, interconnect) remain enabled across
suspend, preventing the platform from reaching its lowest idle state.

Fix this by calling pm_runtime_force_suspend() at the end of
qcom_geni_serial_suspend() so that the runtime-suspend callback is
always executed regardless of the usage count, and by calling
pm_runtime_force_resume() at the start of qcom_geni_serial_resume()
to restore those resources before uart_resume_port() re-opens the
port.

Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260702-add_force_suspend_resume_to_system_sleep_callbacks-v2-1-b79e254a7015@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Praveen Talari 2026-07-02 17:11:50 +05:30 committed by Greg Kroah-Hartman
parent bafe277d6c
commit d0cd9c8d0f
1 changed files with 18 additions and 1 deletions
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19
drivers/tty/serial/qcom_geni_serial.c
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@ -1985,6 +1985,7 @@ static int qcom_geni_serial_suspend(struct device *dev)
struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
struct uart_port *uport = &port->uport;
struct qcom_geni_private_data *private_data = uport->private_data;
int ret;
/*
* This is done so we can hit the lowest possible state in suspend
@ -1994,7 +1995,19 @@ static int qcom_geni_serial_suspend(struct device *dev)
geni_icc_set_tag(&port->se, QCOM_ICC_TAG_ACTIVE_ONLY);
geni_icc_set_bw(&port->se);
}
return uart_suspend_port(private_data->drv, uport);
ret = uart_suspend_port(private_data->drv, uport);
if (ret)
return ret;
/*
* When no_console_suspend is set the console must remain active
* across system sleep, so skip the force suspend path.
*/
if (!console_suspend_enabled && uart_console(uport))
return 0;
return pm_runtime_force_suspend(dev);
}
static int qcom_geni_serial_resume(struct device *dev)
@ -2004,6 +2017,10 @@ static int qcom_geni_serial_resume(struct device *dev)
struct uart_port *uport = &port->uport;
struct qcom_geni_private_data *private_data = uport->private_data;
ret = pm_runtime_force_resume(dev);
if (ret)
return ret;
ret = uart_resume_port(private_data->drv, uport);
if (uart_console(uport)) {
geni_icc_set_tag(&port->se, QCOM_ICC_TAG_ALWAYS);