linux-kernel - [PATCH v2] serial: qcom_geni: Fix pinctrl deadlock on runtime resume

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Message-Id: <20250917185102.3763398-1-praveen.talari@oss.qualcomm.com>
Date: Thu, 18 Sep 2025 00:21:02 +0530
From: Praveen Talari <praveen.talari@....qualcomm.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        Praveen Talari <quic_ptalari@...cinc.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org, alexey.klimov@...aro.org,
        krzk@...nel.org, jorge.ramirez@....qualcomm.com,
        dmitry.baryshkov@....qualcomm.com, andersson@...nel.org
Cc: psodagud@...cinc.com, djaggi@...cinc.com, quic_msavaliy@...cinc.com,
        quic_vtanuku@...cinc.com, quic_arandive@...cinc.com,
        quic_shazhuss@...cinc.com, quic_cchiluve@...cinc.com,
        Praveen Talari <praveen.talari@....qualcomm.com>
Subject: [PATCH v2] serial: qcom_geni: Fix pinctrl deadlock on runtime resume

A stall was observed in disable_irq() during
pinctrl_pm_select_default_state(), triggered by wakeup IRQ being active
while the UART port was not yet active. This led to a hang in
__synchronize_irq(), as shown in the following trace:

Call trace:
    __switch_to+0xe0/0x120
    __schedule+0x39c/0x978
    schedule+0x5c/0xf8
    __synchronize_irq+0x88/0xb4
    disable_irq+0x3c/0x4c
    msm_pinmux_set_mux+0x508/0x644
    pinmux_enable_setting+0x190/0x2dc
    pinctrl_commit_state+0x13c/0x208
    pinctrl_pm_select_default_state+0x4c/0xa4
    geni_se_resources_on+0xe8/0x154
    qcom_geni_serial_runtime_resume+0x4c/0x88
    pm_generic_runtime_resume+0x2c/0x44
    __genpd_runtime_resume+0x30/0x80
    genpd_runtime_resume+0x114/0x29c
    __rpm_callback+0x48/0x1d8
    rpm_callback+0x6c/0x78
    rpm_resume+0x530/0x750
    __pm_runtime_resume+0x50/0x94
    handle_threaded_wake_irq+0x30/0x94
    irq_thread_fn+0x2c/0xa8
    irq_thread+0x160/0x248
    kthread+0x110/0x114
    ret_from_fork+0x10/0x20

To fix this, wakeup IRQ setup is moved from probe to UART startup,
ensuring it is only configured when the port is active. Correspondingly,
the wakeup IRQ is cleared during shutdown. This avoids premature IRQ
disable during pinctrl setup and prevents the observed stall. The probe
and remove pathsare simplified by removing redundant wakeup IRQ handling.

Fixes: 1afa70632c39 ("serial: qcom-geni: Enable PM runtime for serial driver")
Reported-by: Alexey Klimov <alexey.klimov@...aro.org>
Closes: https://lore.kernel.org/all/DC0D53ZTNOBU.E8LSD5E5Z8TX@linaro.org/
Tested-by: Jorge Ramirez <jorge.ramirez@....qualcomm.com>
Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>
---
v1 -> v2:
- remove changes from runtime resume/suspend.
- updated commit text based on changes.
- added new a change w.r.t wakeup IRQ setup.
- verified on RB1 (qrb2210-rb1-core-kit).
---
---
 drivers/tty/serial/qcom_geni_serial.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 0fdda3a1e70b..9c1bd4e5852c 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1160,6 +1160,7 @@ static int setup_fifos(struct qcom_geni_serial_port *port)
 
 static void qcom_geni_serial_shutdown(struct uart_port *uport)
 {
+	struct qcom_geni_serial_port *port = to_dev_port(uport);
 	disable_irq(uport->irq);
 
 	uart_port_lock_irq(uport);
@@ -1168,6 +1169,8 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
 
 	qcom_geni_serial_cancel_tx_cmd(uport);
 	uart_port_unlock_irq(uport);
+	if (port->wakeup_irq > 0)
+		dev_pm_clear_wake_irq(uport->dev);
 }
 
 static void qcom_geni_serial_flush_buffer(struct uart_port *uport)
@@ -1236,6 +1239,13 @@ static int qcom_geni_serial_startup(struct uart_port *uport)
 			return ret;
 	}
 
+	if (port->wakeup_irq > 0) {
+		ret = dev_pm_set_dedicated_wake_irq(uport->dev,
+						    port->wakeup_irq);
+		if (ret)
+			return ret;
+	}
+
 	uart_port_lock_irq(uport);
 	qcom_geni_serial_start_rx(uport);
 	uart_port_unlock_irq(uport);
@@ -1888,17 +1898,8 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	if (ret)
 		goto error;
 
-	if (port->wakeup_irq > 0) {
+	if (port->wakeup_irq > 0)
 		device_init_wakeup(&pdev->dev, true);
-		ret = dev_pm_set_dedicated_wake_irq(&pdev->dev,
-						port->wakeup_irq);
-		if (ret) {
-			device_init_wakeup(&pdev->dev, false);
-			ida_free(&port_ida, uport->line);
-			uart_remove_one_port(drv, uport);
-			goto error;
-		}
-	}
 
 	return 0;
 
@@ -1913,7 +1914,6 @@ static void qcom_geni_serial_remove(struct platform_device *pdev)
 	struct uart_port *uport = &port->uport;
 	struct uart_driver *drv = port->private_data.drv;
 
-	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
 	ida_free(&port_ida, uport->line);
 	uart_remove_one_port(drv, &port->uport);

base-commit: 3e8e5822146bc396d2a7e5fbb7be13271665522a
-- 
2.34.1