[PATCH] PCI: qcom: Disable ASPM L0s for SA8775P

Shawn Guo
2026-04-19T09:39:45Z

Commit f5cd8a929c82 ("PCI: dwc: Remove MSI/MSIX capability for Root Port
if iMSI-RX is used as MSI controller") removed MSI/MSI-X capabilities
from the Root Port on platforms using iMSI-RX (including SA8775P, which
has no msi-parent/msi-map in DT). This causes PME and AER service
drivers to fall back from MSI to INTx.

With INTx-based PME active, the QCN9100 modem endpoint sends PME messages
during D-state transitions early in boot. The level-triggered INTx
assertion coincides with ASPM L0s exit sequencing on SA8775P hardware,
causing Data Link Layer Replay Timer Timeout errors on both sides of the
link.

[ 13.069528] pcieport 0000:00:00.0: PME: Signaling with IRQ 332
[ 13.082436] pcieport 0000:00:00.0: AER: enabled with IRQ 332
[ 13.082447] pcieport 0000:00:00.0: AER: Correctable error message received from 0000:01:00.0
[ 13.101347] pci 0000:01:00.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Transmitter ID)
[ 13.111281] pci 0000:01:00.0: device [17cb:1103] error status/mask=00001000/0000e000
[ 13.111284] pci 0000:01:00.0: [12] Timeout
[ 13.111313] pcieport 0000:00:00.0: AER: Multiple Correctable error message received from 0000:01:00.0
[ 13.130512] pcieport 0000:00:00.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Transmitter ID)
[ 13.130514] pcieport 0000:00:00.0: device [17cb:0115] error status/mask=00001000/0000e000
[ 13.130516] pcieport 0000:00:00.0: [12] Timeout

Fix the PCIe regression on SA8775P/Lemans platform by adding no_l0s = true
to cfg_1_34_0 for SA8775P, so that PCI_EXP_LNKCAP_ASPM_L0S is cleared from
the Root Port and ASPM L0s is prevented from being negotiated.

Fixes: f5cd8a929c82 ("PCI: dwc: Remove MSI/MSIX capability for Root Port if iMSI-RX is used as MSI controller")
Assisted-by: Claude:claude-4-6-sonnet
Signed-off-by: Shawn Guo <shengchao.guo@oss.qualcomm.com>
---
drivers/pci/controller/dwc/pcie-qcom.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index af6bf5cce65b..6a14b5091338 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1473,6 +1473,7 @@ static const struct qcom_pcie_cfg cfg_1_9_0 = {
static const struct qcom_pcie_cfg cfg_1_34_0 = {
.ops = &ops_1_9_0,
.override_no_snoop = true,
+ .no_l0s = true,
};

static const struct qcom_pcie_cfg cfg_2_1_0 = {
--
2.43.0