CVE-2026-53051

In the Linux kernel, the following vulnerability has been resolved:

PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on

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.