PCI: tegra: Move "dbi" accesses to post common DWC initialization

commit a0fd361d ("PCI: dwc: Move "dbi", "dbi2", and "addr_space"
resource setup into common code") moved the code that sets up dbi_base
to DWC common code thereby creating a requirement to not access the "dbi"
region before calling common DWC initialization code. But, Tegra194
already had some code that programs some of the "dbi" registers resulting
in system crash. This patch addresses that issue by refactoring the code
to have accesses to the "dbi" region only after common DWC initialization.

Link: https://lore.kernel.org/r/20201125192234.2270-1-vidyas@nvidia.com
Fixes: a0fd361d ("PCI: dwc: Move "dbi", "dbi2", and "addr_space" resource setup into common code")
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thierry Reding <treding@nvidia.com>

drivers/pci/controller/dwc/pcie-tegra194.c

@@ -859,6 +859,16 @@ static void tegra_pcie_prepare_host(struct pcie_port *pp)
 	struct tegra_pcie_dw *pcie = to_tegra_pcie(pci);
 	u32 val;
 
+	if (!pcie->pcie_cap_base)
+		pcie->pcie_cap_base = dw_pcie_find_capability(&pcie->pci,
+							      PCI_CAP_ID_EXP);
+
+	/* Disable ASPM-L1SS advertisement if there is no CLKREQ routing */
+	if (!pcie->supports_clkreq) {
+		disable_aspm_l11(pcie);
+		disable_aspm_l12(pcie);
+	}
+
 	val = dw_pcie_readl_dbi(pci, PCI_IO_BASE);
 	val &= ~(IO_BASE_IO_DECODE | IO_BASE_IO_DECODE_BIT8);
 	dw_pcie_writel_dbi(pci, PCI_IO_BASE, val);
@@ -1382,15 +1392,6 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
 
 	reset_control_deassert(pcie->core_rst);
 
-	pcie->pcie_cap_base = dw_pcie_find_capability(&pcie->pci,
-						      PCI_CAP_ID_EXP);
-
-	/* Disable ASPM-L1SS advertisement as there is no CLKREQ routing */
-	if (!pcie->supports_clkreq) {
-		disable_aspm_l11(pcie);
-		disable_aspm_l12(pcie);
-	}
-
 	return ret;
 
 fail_phy: