phy: qcom-qusb2: Fix NULL pointer dereference on early suspend

Enabling runtime PM before attaching the QPHY instance as driver data
can lead to a NULL pointer dereference in runtime PM callbacks that
expect valid driver data. There is a small window where the suspend
callback may run after PM runtime enabling and before runtime forbid.
This causes a sporadic crash during boot:

```
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a1
[...]
CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.16.7+ #116 PREEMPT
Workqueue: pm pm_runtime_work
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : qusb2_phy_runtime_suspend+0x14/0x1e0 [phy_qcom_qusb2]
lr : pm_generic_runtime_suspend+0x2c/0x44
[...]
```

Attach the QPHY instance as driver data before enabling runtime PM to
prevent NULL pointer dereference in runtime PM callbacks.

Reorder pm_runtime_enable() and pm_runtime_forbid() to prevent a
short window where an unnecessary runtime suspend can occur.

Use the devres-managed version to ensure PM runtime is symmetrically
disabled during driver removal for proper cleanup.

Fixes: 891a96f65ac3 ("phy: qcom-qusb2: Add support for runtime PM")
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Link: https://patch.msgid.link/20251219085640.114473-1-loic.poulain@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/phy/qualcomm/phy-qcom-qusb2.c b/drivers/phy/qualcomm/phy-qcom-qusb2.c
index b5514a32ff8ff5bdb4204e6e78884bdf9288c002..eb93015be841f5b85ddb345010fb12756e225d45 100644 (file)
--- a/drivers/phy/qualcomm/phy-qcom-qusb2.c
+++ b/drivers/phy/qualcomm/phy-qcom-qusb2.c
@@ -1093,29 +1093,29 @@ static int qusb2_phy_probe(struct platform_device *pdev)
                or->hsdisc_trim.override = true;
        }
 
-       pm_runtime_set_active(dev);
-       pm_runtime_enable(dev);
+       dev_set_drvdata(dev, qphy);
+
        /*
-        * Prevent runtime pm from being ON by default. Users can enable
-        * it using power/control in sysfs.
+        * Enable runtime PM support, but forbid it by default.
+        * Users can allow it again via the power/control attribute in sysfs.
         */
+       pm_runtime_set_active(dev);
        pm_runtime_forbid(dev);
+       ret = devm_pm_runtime_enable(dev);
+       if (ret)
+               return ret;
 
        generic_phy = devm_phy_create(dev, NULL, &qusb2_phy_gen_ops);
        if (IS_ERR(generic_phy)) {
                ret = PTR_ERR(generic_phy);
                dev_err(dev, "failed to create phy, %d\n", ret);
-               pm_runtime_disable(dev);
                return ret;
        }
        qphy->phy = generic_phy;
 
-       dev_set_drvdata(dev, qphy);
        phy_set_drvdata(generic_phy, qphy);
 
        phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
-       if (IS_ERR(phy_provider))
-               pm_runtime_disable(dev);
 
        return PTR_ERR_OR_ZERO(phy_provider);
 }