[PATCH v2 0/2] PCI: qcom: Implement shutdown() to avoid SMMU/NoC errors on reboot

[PATCH v2 0/2] PCI: qcom: Implement shutdown() to avoid SMMU/NoC errors on reboot

[Krishna Chaitanya Chundru]

During system shutdown/reboot, power/clocks to the PCIe controller get
removed regardless of link state. If the link is still up when that
happens, it can trigger SMMU or NoC errors.

This series adds a shutdown() callback to the Qualcomm PCIe host driver
that forces the link into L2/D3cold before shutdown proceeds, reusing
the existing suspend_noirq() path.

Patch 1 makes dw_pcie_suspend_noirq() skip the D3cold capability check
during shutdown/reboot, since that check can fail and leave the link up
if any endpoint hasn't suspended yet.

Patch 2 adds qcom_pcie_shutdown() and wires it up as .shutdown.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
Changes in v2:
1) don't remove the endpoint pci dev's only keep link in D3cold.
Link to v1: https://lore.kernel.org/all/20250401-shutdown-v1-1-f699859403ae@oss.qualcomm.com/

---
Krishna Chaitanya Chundru (1):
      PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check

Manivannan Sadhasivam (1):
      PCI: qcom: Implement shutdown() callback

 drivers/pci/controller/dwc/pcie-designware-host.c | 18 ++++++++++++++++--
 drivers/pci/controller/dwc/pcie-qcom.c            | 10 ++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
---
base-commit: c1366b72ad4e87be60b57b74635a3a0bc58d2b0b
change-id: 20260822-shutdown-fe8139dff2b7

Best regards,
--  
Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>

[PATCH v2 1/2] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check

[Krishna Chaitanya Chundru]

dw_pcie_suspend_noirq() normally calls pci_host_common_d3cold_possible()
to check whether every downstream endpoint can be put into D3cold before
bothering to move the link to L2. If no endpoint supports it, the
function returns early and leaves the link up.

Querying D3cold support during shutdown is actively harmful, not just
slow: pci_host_common_d3cold_possible() requires every active endpoint
to already be in PCI_D3hot, and returns false otherwise. If any endpoint
is still in D0 -- which is common, since endpoint drivers aren't
guaranteed to have suspended by the time the host's shutdown path runs
the check fails and dw_pcie_suspend_noirq() returns early without ever
moving the link to L2, leaving it up right up to the point where the
system cuts power/clocks to the controller.

Detect the shutdown/reboot case via system_state and skip straight to
forcing the link into L2, the same sequence used for the D3cold-capable
case.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 06722259d2e3..98cd9dd2c7d7 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -13,6 +13,7 @@
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/irq-msi-lib.h>
 #include <linux/irqdomain.h>
+#include <linux/kernel.h>
 #include <linux/msi.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
@@ -1222,16 +1223,29 @@ static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
 
 int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 {
-	bool pme_capable = false;
+	bool shutdown = system_state == SYSTEM_HALT ||
+			system_state == SYSTEM_POWER_OFF ||
+			system_state == SYSTEM_RESTART;
+	bool d3cold, pme_capable = false;
 	int ret = 0;
 	u32 val;
 
 	if (!dw_pcie_link_up(pci))
 		goto stop_link;
 
-	if (!pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable))
+	/*
+	 * During reboot/halt/poweroff the link is going away regardless, so
+	 * force L2 entry without checking whether endpoints have transitioned
+	 * to D3hot -- there's no point walking the bus to find out.
+	 */
+	if (shutdown)
+		goto d3cold;
+
+	d3cold = pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable);
+	if (!d3cold)
 		return 0;
 
+d3cold:
 	if (pci->pp.ops->pme_turn_off) {
 		pci->pp.ops->pme_turn_off(&pci->pp);
 	} else {

-- 
2.34.1

Re: [PATCH v2 1/2] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The patch breaks Wake-on-LAN and PME from S4/S5 (hibernation/poweroff) by unconditionally powering off PCIe endpoints and disabling auxiliary power.
--

--- Patch [1]: [PATCH v2 1/2] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check ---
commit abaf02ec8187ffca064828adacb9cade46a5b293
Author: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>

PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check

This commit modifies dw_pcie_suspend_noirq() to force the PCIe link into L2
during system shutdown or reboot. It bypasses the pci_host_common_d3cold_possible()
check to prevent the link from staying up when endpoints fail to suspend.

> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
[ ... ]
> @@ -1222,16 +1223,29 @@ static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
>  
>  int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>  {
> -	bool pme_capable = false;
> +	bool shutdown = system_state == SYSTEM_HALT ||
> +			system_state == SYSTEM_POWER_OFF ||
> +			system_state == SYSTEM_RESTART;
> +	bool d3cold, pme_capable = false;
>  	int ret = 0;
>  	u32 val;
>  
>  	if (!dw_pcie_link_up(pci))
>  		goto stop_link;
>  
> -	if (!pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable))
> +	/*
> +	 * During reboot/halt/poweroff the link is going away regardless, so
> +	 * force L2 entry without checking whether endpoints have transitioned
> +	 * to D3hot -- there's no point walking the bus to find out.
> +	 */
> +	if (shutdown)
> +		goto d3cold;

[Severity: High]
When shutdown is true, the code jumps straight to the d3cold label, entirely
bypassing the pci_host_common_d3cold_possible() check. Because pme_capable
is initialized to false, doesn't this mean it will unconditionally remain
false during shutdown or poweroff?

If pme_capable remains false, later in dw_pcie_suspend_noirq() under the
stop_link label, we set:

	pci->pp.skip_pwrctrl_off = pme_capable;
	dw_pcie_stop_link(pci);

Will this cause the host driver to explicitly cut auxiliary power to the
endpoints, breaking Wake-on-LAN and PME generation from S4 (hibernation)
or S5 (poweroff) for devices that were correctly configured for wakeup?

> +
> +	d3cold = pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable);
> +	if (!d3cold)
>  		return 0;
>  
> +d3cold:
>  	if (pci->pp.ops->pme_turn_off) {
>  		pci->pp.ops->pme_turn_off(&pci->pp);
>  	} else {

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260822-shutdown-v2-0-520a68f1b4a5@oss.qualcomm.com?part=1

[PATCH v2 2/2] PCI: qcom: Implement shutdown() callback

[Krishna Chaitanya Chundru]

From: Manivannan Sadhasivam <mani@kernel.org>

PCIe host controllers should bring the link down cleanly before system
shutdown/reboot proceeds to remove power/clocks from the controller.
Without this, the link may still be up and endpoints still have
transactions in flight when power/clocks are cut, which can trip SMMU
translation faults or NoC protocol errors.

Reuse dw_pcie_suspend_noirq() in the shutdown path to force the link
into L2, putting it into D3cold.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index d8eb52857f69..f6a0cbb6a49e 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -2156,6 +2156,15 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void qcom_pcie_shutdown(struct platform_device *pdev)
+{
+	struct qcom_pcie *pcie = platform_get_drvdata(pdev);
+
+	dw_pcie_suspend_noirq(pcie->pci);
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+}
+
 static int qcom_pcie_suspend_noirq(struct device *dev)
 {
 	struct qcom_pcie *pcie;
@@ -2337,5 +2346,6 @@ static struct platform_driver qcom_pcie_driver = {
 		.pm = &qcom_pcie_pm_ops,
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
+	.shutdown = qcom_pcie_shutdown,
 };
 builtin_platform_driver(qcom_pcie_driver);

-- 
2.34.1

Re: [PATCH v2 2/2] PCI: qcom: Implement shutdown() callback

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] The qcom_pcie_shutdown() callback unconditionally dereferences the `pcie` pointer, which will cause a kernel panic for firmware-managed devices.
- [Medium] Calling asynchronous pm_runtime_put() immediately before pm_runtime_disable() risks cancelling pending suspend operations and violates Power Management guidelines.
--

--- Patch [2]: [PATCH v2 2/2] PCI: qcom: Implement shutdown() callback ---
commit 321e5283c22739b1af3a513ad41fac675e68553f
Author: Manivannan Sadhasivam <mani@kernel.org>

PCI: qcom: Implement shutdown() callback

This commit implements a shutdown callback for the Qualcomm PCIe controller.
It reuses dw_pcie_suspend_noirq() to safely bring down the link and transition
to D3cold during system shutdown or reboot.

> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index d8eb52857f69c..f6a0cbb6a49e8 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -2156,6 +2156,15 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  	return ret;
>  }
>  
> +static void qcom_pcie_shutdown(struct platform_device *pdev)
> +{
> +	struct qcom_pcie *pcie = platform_get_drvdata(pdev);
> +
> +	dw_pcie_suspend_noirq(pcie->pci);

[Severity: High]
Can pcie be NULL here? In qcom_pcie_probe(), if the device is
firmware_managed, the probe returns 0 early without allocating the pcie
structure or calling platform_set_drvdata(). Will this result in a NULL
pointer dereference during shutdown on those platforms?

> +	pm_runtime_put(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);

[Severity: Medium]
Does using the asynchronous pm_runtime_put() here risk cancelling the pending
suspend operation when pm_runtime_disable() is immediately called? Should this
use pm_runtime_put_sync() instead to ensure the suspend completes before
runtime PM is disabled?

> +}
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260822-shutdown-v2-0-520a68f1b4a5@oss.qualcomm.com?part=2