Commit 1ca52c09 authored by Loic Poulain's avatar Loic Poulain Committed by Vinod Koul
Browse files

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: 891a96f6 ("phy: qcom-qusb2: Add support for runtime PM")
Signed-off-by: default avatarLoic Poulain <loic.poulain@oss.qualcomm.com>
Reviewed-by: default avatarDmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: default avatarAbel Vesa <abel.vesa@oss.qualcomm.com>
Link: https://patch.msgid.link/20251219085640.114473-1-loic.poulain@oss.qualcomm.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 8becf917

drivers/phy/qualcomm/phy-qcom-qusb2.c

+8 −8
Original line number Diff line number Diff line
@@ -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);

}