[PATCH] phy: qcom: qmp-combo: hold a runtime PM reference in the typec callbacks

[Oleg Keri]

qmp_combo_typec_switch_set() and qmp_combo_typec_mux_set() tear the common
block down and bring it straight back up, calling qmp_combo_com_exit() and
qmp_combo_com_init() with force=true.  Both release and re-acquire the PHY
clocks.

Unlike the PHY operations, which the PHY core always invokes with a
runtime PM reference held - phy_pm_runtime_get_sync() in phy_init(),
phy_exit() and phy_power_on() - these two are typec_switch and typec_mux
callbacks and hold no such reference.  Releasing the clocks is then enough
to drop the device's last reference, so clk_core_unprepare() runs
pm_runtime_idle() and re-enters the driver through
qmp_combo_runtime_suspend(), which disables the very clocks that are being
torn down:

  gcc_usb3_prim_phy_pipe_clk already disabled
  WARNING: drivers/clk/clk.c:1259 at clk_core_disable+0x298/0x300
  Workqueue: events_freezable pmic_glink_altmode_worker
   clk_disable
   qmp_combo_runtime_suspend
   pm_generic_runtime_suspend
   genpd_runtime_suspend
   rpm_suspend
   rpm_idle
   __pm_runtime_idle
   clk_core_unprepare
   clk_core_unprepare
   clk_core_unprepare

qmp_combo_runtime_suspend() only checks init_count, which is still
non-zero at that point, so it proceeds and the clock enable and prepare
counts underflow.

Runtime PM is forbidden at probe, so this only becomes reachable once
userspace opts in through power/control - which is exactly what the
comment above pm_runtime_forbid() invites it to do.

Hold a runtime PM reference across the teardown and bringup so releasing
the clocks cannot re-enter the driver's own suspend callback.

Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
Signed-off-by: Oleg Keri <okerixx@xxxxxxxxx>
---
 drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
index d77fe94b312c..bf4d29fe1719 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
@@ -16,6 +16,7 @@
 #include <linux/of_graph.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
@@ -4930,6 +4931,8 @@ static int qmp_combo_typec_switch_set(struct typec_switch_dev *sw,
 	qmp->orientation = orientation;
 
 	if (qmp->init_count) {
+		guard(pm_runtime_active)(qmp->dev);
+
 		if (qmp->usb_init_count)
 			qmp_combo_usb_power_off(qmp->usb_phy);
 		qmp_combo_com_exit(qmp, true);
@@ -4997,6 +5000,8 @@ static int qmp_combo_typec_mux_set(struct typec_mux_dev *mux, struct typec_mux_s
 	qmp->qmpphy_mode = new_mode;
 
 	if (qmp->init_count) {
+		guard(pm_runtime_active)(qmp->dev);
+
 		if (qmp->usb_init_count)
 			qmp_combo_usb_power_off(qmp->usb_phy);
 
-- 
2.55.0


base-commit: df2908090cda368b01ff43709f51890076c56157