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serial: qcom-geni: remove .pm callback, use runtime PM in startup/shutdown

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The driver currently relies on qcom_geni_serial_pm() through the
uart_ops.pm callback to manage runtime PM references. However, the
callback has a void return type, so failures from
pm_runtime_resume_and_get() cannot be propagated to the caller.

As a result, startup() may continue and access hardware even when the
runtime PM resume operation failed, leading to register accesses while
the device is not powered.

Move runtime PM acquisition to qcom_geni_serial_startup() and release it
to qcom_geni_serial_shutdown(). Since startup() can return an error, PM
resume failures are now detected and propagated before any hardware
initialization is performed. The startup/shutdown pair also provides a
natural place to balance runtime PM references for normal port usage.

During probe, uart_add_one_port() may configure the port before any user
opens the TTY, meaning startup() has not yet been called. To keep the
hardware powered during port registration, acquire a runtime PM
reference with pm_runtime_resume_and_get() before uart_add_one_port()
and release it with pm_runtime_put() afterwards.

By moving runtime PM handling out of uart_ops.pm, resume failures are no
longer silently ignored and all hardware accesses are guaranteed to
occur while the device is powered.

Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260720-remove_uart_change_state-v2-1-30153ce4333b@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Praveen Talari 2026-07-20 14:27:52 +05:30 committed by Greg Kroah-Hartman
parent 1145d1a070
commit aee1f94dab
1 changed files with 18 additions and 19 deletions
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37
drivers/tty/serial/qcom_geni_serial.c
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@ -1190,6 +1190,8 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
qcom_geni_serial_cancel_tx_cmd(uport);
uart_port_unlock_irq(uport);
pm_runtime_put_sync(uport->dev);
}
static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
@ -1263,10 +1265,18 @@ static int qcom_geni_serial_startup(struct uart_port *uport)
struct qcom_geni_serial_port *port = to_dev_port(uport);
struct tty_port *tport = &uport->state->port;
ret = pm_runtime_resume_and_get(uport->dev);
if (ret < 0) {
dev_err(uport->dev, "Failed to resume and get %d\n", ret);
return ret;
}
if (!port->setup) {
ret = qcom_geni_serial_port_setup(uport);
if (ret)
if (ret) {
pm_runtime_put_sync(uport->dev);
return ret;
}
}
/*
@ -1752,22 +1762,6 @@ static int geni_serial_resource_init(struct uart_port *uport)
return 0;
}
static void qcom_geni_serial_pm(struct uart_port *uport,
unsigned int new_state, unsigned int old_state)
{
/* If we've never been called, treat it as off */
if (old_state == UART_PM_STATE_UNDEFINED)
old_state = UART_PM_STATE_OFF;
if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF)
pm_runtime_resume_and_get(uport->dev);
else if (new_state == UART_PM_STATE_OFF &&
old_state == UART_PM_STATE_ON)
pm_runtime_put_sync(uport->dev);
}
/**
* qcom_geni_rs485_config - Configure RS485 settings for the UART port
* @uport: Pointer to the UART port structure
@ -1806,7 +1800,6 @@ static const struct uart_ops qcom_geni_console_pops = {
.poll_put_char = qcom_geni_serial_poll_put_char,
.poll_init = qcom_geni_serial_poll_init,
#endif
.pm = qcom_geni_serial_pm,
};
static const struct uart_ops qcom_geni_uart_pops = {
@ -1823,7 +1816,6 @@ static const struct uart_ops qcom_geni_uart_pops = {
.type = qcom_geni_serial_get_type,
.set_mctrl = qcom_geni_serial_set_mctrl,
.get_mctrl = qcom_geni_serial_get_mctrl,
.pm = qcom_geni_serial_pm,
};
static int qcom_geni_serial_panic_notifier(struct notifier_block *nb,
@ -1973,7 +1965,14 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
devm_pm_runtime_enable(port->se.dev);
ret = pm_runtime_resume_and_get(uport->dev);
if (ret < 0) {
dev_err(uport->dev, "Failed to resume and get %d\n", ret);
goto error;
}
ret = uart_add_one_port(drv, uport);
pm_runtime_put(uport->dev);
if (ret)
goto error;