[PATCH] usb: typec: ucsi: ucsi_glink: Prevent suspend during UCSI notification handling

[Jishnu Prakash]

When the system is suspended and a UCSI event arrives (such as USB plug-in),
the GLINK interrupt (with IRQF_NO_SUSPEND flag) fires and it eventually calls
the pmic_glink_ucsi_callback(), which schedules notify_work to handle the
connector change. However, since no wakeup source is held, the system can
re-enter suspend soon after the interrupt handler returns, before notify_work
has completed running, and the USB plug-in event would not be handled.

There was an earlier attempt to address this at the GLINK driver level, by
making the GLINK interrupt wakeup-capable, ("rpmsg: glink: Make glink smem
interrupt wakeup capable") [1], but upstream reviewers suggested a
different approach, preferring wakeup logic to be handled in the client driver.

To avoid losing UCSI notifications in this way, register ucsi_glink
as a wakeup-capable device in the probe, and call pm_wakeup_ws_event()
with hard=true before scheduling notify_work. The hard wakeup aborts any
in-progress suspend, and the timed wakeup source keeps the system
awake long enough for the notify_work call to run.

[1] https://lore.kernel.org/all/20240603073648.3475123-1-quic_deesin@xxxxxxxxxxx/

Signed-off-by: Jishnu Prakash <jishnu.prakash@xxxxxxxxxxxxxxxx>
---
 drivers/usb/typec/ucsi/ucsi_glink.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/usb/typec/ucsi/ucsi_glink.c b/drivers/usb/typec/ucsi/ucsi_glink.c
index 12e07b9fe622..7fa039f0a2ba 100644
--- a/drivers/usb/typec/ucsi/ucsi_glink.c
+++ b/drivers/usb/typec/ucsi/ucsi_glink.c
@@ -7,6 +7,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
+#include <linux/pm_wakeup.h>
 #include <linux/property.h>
 #include <linux/soc/qcom/pdr.h>
 #include <linux/usb/typec_mux.h>
@@ -26,6 +27,12 @@
 #define UC_UCSI_WRITE_BUF_REQ           0x12
 #define UC_UCSI_USBC_NOTIFY_IND         0x13
 
+/*
+ * Wakeup timeout to allow USB event notification processing to
+ * complete before device suspends.
+ */
+#define UCSI_GLINK_WAKEUP_TIMEOUT_MS	50
+
 struct ucsi_read_buf_req_msg {
 	struct pmic_glink_hdr   hdr;
 };
@@ -342,6 +349,8 @@ static void pmic_glink_ucsi_callback(const void *data, size_t len, void *priv)
 		pmic_glink_ucsi_write_ack(ucsi, data, len);
 		break;
 	case UC_UCSI_USBC_NOTIFY_IND:
+		pm_wakeup_ws_event(ucsi->dev->power.wakeup,
+				   UCSI_GLINK_WAKEUP_TIMEOUT_MS, true);
 		schedule_work(&ucsi->notify_work);
 		break;
 	}
@@ -401,6 +410,8 @@ static int pmic_glink_ucsi_probe(struct auxiliary_device *adev,
 	ucsi->dev = dev;
 	dev_set_drvdata(dev, ucsi);
 
+	device_init_wakeup(dev, true);
+
 	INIT_WORK(&ucsi->notify_work, pmic_glink_ucsi_notify);
 	INIT_WORK(&ucsi->register_work, pmic_glink_ucsi_register);
 	init_completion(&ucsi->read_ack);

---
base-commit: 2cb6eac064c8334418a76999468f68696a8dfe71
change-id: 20260710-ucsi_glink_wakeup-07e6bd23256b

Best regards,
--  
Jishnu Prakash <jishnu.prakash@xxxxxxxxxxxxxxxx>