* [PATCH v4 1/2] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check
2026-08-26 7:16 [PATCH v4 0/2] PCI: qcom: Implement shutdown() to avoid SMMU/NoC errors on reboot Krishna Chaitanya Chundru
@ 2026-08-26 7:16 ` Krishna Chaitanya Chundru
2026-08-26 7:16 ` [PATCH v4 2/2] PCI: qcom: Implement shutdown() callback Krishna Chaitanya Chundru
1 sibling, 0 replies; 3+ messages in thread
From: Krishna Chaitanya Chundru @ 2026-08-26 7:16 UTC (permalink / raw)
To: Jingoo Han, Manivannan Sadhasivam, Lorenzo Pieralisi,
Krzysztof Wilczyński, Rob Herring, Bjorn Helgaas
Cc: konrad.dybcio, linux-pci, linux-kernel, linux-arm-msm,
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. Still call
pci_host_common_d3cold_possible() unconditionally, since it's also how
"pme_capable" gets set, but ignore its return value when shutting down
and force L2 entry regardless.
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
drivers/pci/controller/dwc/pcie-designware-host.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index f5a38e6fd8d7..5d07a742faa1 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>
@@ -1224,14 +1225,25 @@ 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. Call
+ * pci_host_common_d3cold_possible() anyway (ignoring its return value
+ * in the shutdown case) since it's also how "pme_capable" gets set.
+ */
+ d3cold = pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable);
+ if (!d3cold && !shutdown)
return 0;
if (pci->pp.ops->pme_turn_off) {
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v4 2/2] PCI: qcom: Implement shutdown() callback
2026-08-26 7:16 [PATCH v4 0/2] PCI: qcom: Implement shutdown() to avoid SMMU/NoC errors on reboot Krishna Chaitanya Chundru
2026-08-26 7:16 ` [PATCH v4 1/2] PCI: dwc: Force L2 link entry on shutdown/reboot without D3cold check Krishna Chaitanya Chundru
@ 2026-08-26 7:16 ` Krishna Chaitanya Chundru
1 sibling, 0 replies; 3+ messages in thread
From: Krishna Chaitanya Chundru @ 2026-08-26 7:16 UTC (permalink / raw)
To: Jingoo Han, Manivannan Sadhasivam, Lorenzo Pieralisi,
Krzysztof Wilczyński, Rob Herring, Bjorn Helgaas
Cc: konrad.dybcio, linux-pci, linux-kernel, linux-arm-msm,
Krishna Chaitanya Chundru, Manivannan Sadhasivam
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.
device_shutdown() runs with interrupts enabled, unlike suspend_noirq().
Mask the chained MSI IRQ(s) and the Global IRQ before tearing down the
link and clocks/PHY, since a late/spurious interrupt could otherwise
reach a handler that touches now-unclocked PARF/DBI registers.
Firmware-managed (ECAM) Root Complexes own their own link teardown and
clock/PHY shutdown; for those, only mask the MSI IRQs.
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 | 53 ++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index b58a607b713f..fad2f4e2d6be 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1924,6 +1924,9 @@ static int qcom_pcie_ecam_host_init(struct pci_config_window *cfg)
pp->use_imsi_rx = true;
dw_pcie_msi_init(pp);
+ /* Stash pci so qcom_pcie_shutdown() can mask the MSI IRQ(s) later */
+ platform_set_drvdata(to_platform_device(dev), pci);
+
return devm_add_action_or_reset(dev, qcom_pci_free_msi, pp);
}
@@ -2337,6 +2340,55 @@ static int qcom_pcie_probe(struct platform_device *pdev)
return ret;
}
+static void qcom_pcie_mask_msi_irqs(struct dw_pcie_rp *pp)
+{
+ u32 ctrl;
+
+ /*
+ * Mask the chained MSI IRQ(s) before tearing down the link and
+ * clocks/PHY. Unlike suspend_noirq(), device_shutdown() runs with
+ * interrupts enabled, so a late/spurious MSI could otherwise hit
+ * dw_chained_msi_isr() and touch DBI registers after the controller
+ * is powered off.
+ */
+ for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++) {
+ if (pp->msi_irq[ctrl] > 0)
+ disable_irq(pp->msi_irq[ctrl]);
+ }
+}
+
+static void qcom_pcie_shutdown(struct platform_device *pdev)
+{
+ const struct qcom_pcie_cfg *pcie_cfg = of_device_get_match_data(&pdev->dev);
+ struct qcom_pcie *pcie;
+
+ if (pcie_cfg && pcie_cfg->firmware_managed) {
+ /*
+ * Firmware owns the link teardown and clock/PHY shutdown in
+ * this mode; Linux only owns the chained MSI IRQ(s), which
+ * still need to be masked off before shutdown proceeds.
+ */
+ struct dw_pcie *pci = platform_get_drvdata(pdev);
+
+ if (pci)
+ qcom_pcie_mask_msi_irqs(&pci->pp);
+ return;
+ }
+
+ pcie = platform_get_drvdata(pdev);
+ if (pcie) {
+ qcom_pcie_mask_msi_irqs(&pcie->pci->pp);
+
+ if (pcie->global_irq)
+ disable_irq(pcie->global_irq);
+
+ dw_pcie_suspend_noirq(pcie->pci);
+ }
+
+ pm_runtime_put_sync(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+}
+
static int qcom_pcie_suspend_noirq(struct device *dev)
{
struct qcom_pcie *pcie;
@@ -2519,5 +2571,6 @@ 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
^ permalink raw reply related [flat|nested] 3+ messages in thread