PCI: qcom: Remove MSI-X Capability for Root Ports

On some platforms like Glymur, the hardware does not support MSI-X in RC
mode, yet still exposes the MSI-X capability. However, it omits the
required MSI-X Table and PBA structures.

This mismatch can lead to issues where the PCIe port driver requests MSI-X
instead of MSI, causing the Root Port to trigger interrupts by writing to
an uninitialized address, resulting in SMMU faults.

To address this, remove MSI-X capability unconditionally for Root Ports of
all SoCs as none of the Qcom PCIe Root Ports support MSI-X.

Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
[mani: updated description]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20251109-remove_cap-v1-4-2208f46f4dc2@oss.qualcomm.com

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 7b92e7a1c0d9364a9cefe1450818f9cbfc7fd3ac..8b8948fef386d927cf55f049521acb96ccbc4be5 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1316,6 +1316,8 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
                        goto err_disable_phy;
        }
 
+       dw_pcie_remove_capability(pcie->pci, PCI_CAP_ID_MSIX);
+
        qcom_ep_reset_deassert(pcie);
 
        if (pcie->cfg->ops->config_sid) {