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charset="utf-8" When PERST# is deasserted twice (assert -> deassert -> assert -> deassert), a CBB (Control Backbone) timeout occurs at DBI register offset 0x8bc (PCIE_MISC_CONTROL_1_OFF). This happens because pci_epc_deinit_notify() and dw_pcie_ep_cleanup() are called before reset_control_deassert() powers on the controller core. The call chain that causes the timeout: pex_ep_event_pex_rst_deassert() pci_epc_deinit_notify() pci_epf_test_epc_deinit() pci_epf_test_clear_bar() pci_epc_clear_bar() dw_pcie_ep_clear_bar() __dw_pcie_ep_reset_bar() dw_pcie_dbi_ro_wr_en() <- Accesses 0x8bc DBI register reset_control_deassert(pcie->core_rst) <- Core powered on HERE The DBI registers, including PCIE_MISC_CONTROL_1_OFF (0x8bc), are only accessible after the controller core is powered on via reset_control_deassert(pcie->core_rst). Accessing them before this point results in a CBB timeout because the hardware is not yet operational. Fix this by moving pci_epc_deinit_notify() and dw_pcie_ep_cleanup() to after reset_control_deassert(pcie->core_rst), ensuring the controller is fully powered on before any DBI register accesses occur. Fixes: 40e2125381dc ("PCI: tegra194: Move controller cleanups to pex_ep_eve= nt_pex_rst_deassert()") Signed-off-by: Manikanta Maddireddy --- V5: * None V4: * None V3: * None V2: * None drivers/pci/controller/dwc/pcie-tegra194.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/contr= oller/dwc/pcie-tegra194.c index 3924ac123183..bc9a66ba53e2 100644 --- a/drivers/pci/controller/dwc/pcie-tegra194.c +++ b/drivers/pci/controller/dwc/pcie-tegra194.c @@ -1742,10 +1742,6 @@ static void pex_ep_event_pex_rst_deassert(struct teg= ra_pcie_dw *pcie) goto fail_phy; } =20 - /* Perform cleanup that requires refclk */ - pci_epc_deinit_notify(pcie->pci.ep.epc); - dw_pcie_ep_cleanup(&pcie->pci.ep); - /* Clear any stale interrupt statuses */ appl_writel(pcie, 0xFFFFFFFF, APPL_INTR_STATUS_L0); appl_writel(pcie, 0xFFFFFFFF, APPL_INTR_STATUS_L1_0_0); @@ -1806,6 +1802,10 @@ static void pex_ep_event_pex_rst_deassert(struct teg= ra_pcie_dw *pcie) =20 reset_control_deassert(pcie->core_rst); =20 + /* Perform cleanup that requires refclk and core reset deasserted */ + pci_epc_deinit_notify(pcie->pci.ep.epc); + dw_pcie_ep_cleanup(&pcie->pci.ep); + if (pcie->update_fc_fixup) { val =3D dw_pcie_readl_dbi(pci, CFG_TIMER_CTRL_MAX_FUNC_NUM_OFF); val |=3D 0x1 << CFG_TIMER_CTRL_ACK_NAK_SHIFT; --=20 2.34.1