[PATCH 07/11] PCI: tegra194: Always disable Tegra234 Endpoint L1.2

[Manikanta Maddireddy <mmaddireddy@nvidia.com>]

Tegra234 Endpoint mode must not advertise L1.2 because exiting L1.2 can
bring the link down. That hardware workaround is required regardless of
whether the endpoint kernel is built with CONFIG_PCIEASPM.

Move the L1.2 capability masking out of init_host_aspm(), which is compiled
out when CONFIG_PCIEASPM is disabled, and apply it from the common
initialization paths.

Fixes: f59df1d9e6bd ("PCI: tegra194: Disable L1.2 capability of Tegra234 EP")
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 47 +++++++++++++---------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index b35d9456e9de..f8e39459db41 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -611,6 +611,33 @@ static struct pci_ops tegra_pci_ops = {
 	.write = tegra_pcie_dw_wr_own_conf,
 };
 
+/*
+ * Disable L1.2 capability advertisement for Tegra234 Endpoint mode.
+ * Tegra234 has a hardware bug where during L1.2 exit, the UPHY PLL is
+ * powered up immediately without waiting for REFCLK to stabilize. This causes
+ * the PLL to fail to lock to the correct frequency, resulting in PCIe link
+ * loss. Since there is no hardware fix available, prevent the Endpoint from
+ * advertising L1.2 support so the host will not attempt to enter L1.2 with
+ * this Endpoint.
+ */
+static void tegra_pcie_disable_ep_l1_2(struct tegra_pcie_dw *pcie)
+{
+	struct dw_pcie *pci = &pcie->pci;
+	u32 l1ss, val;
+
+	if (!pcie->of_data->disable_l1_2 ||
+	    pcie->of_data->mode != DW_PCIE_EP_TYPE)
+		return;
+
+	l1ss = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_L1SS);
+	if (!l1ss)
+		return;
+
+	val = dw_pcie_readl_dbi(pci, l1ss + PCI_L1SS_CAP);
+	val &= ~(PCI_L1SS_CAP_PCIPM_L1_2 | PCI_L1SS_CAP_ASPM_L1_2);
+	dw_pcie_writel_dbi(pci, l1ss + PCI_L1SS_CAP, val);
+}
+
 #if defined(CONFIG_PCIEASPM)
 static inline u32 event_counter_prog(struct tegra_pcie_dw *pcie, u32 event)
 {
@@ -694,25 +721,6 @@ static void init_host_aspm(struct tegra_pcie_dw *pcie)
 
 		if (pcie->supports_clkreq)
 			pci->l1ss_support = true;
-
-		/*
-		 * Disable L1.2 capability advertisement for Tegra234 Endpoint
-		 * mode. Tegra234 has a hardware bug where during L1.2 exit,
-		 * the UPHY PLL is powered up immediately without waiting for
-		 * REFCLK to stabilize. This causes the PLL to fail to lock to
-		 * the correct frequency, resulting in PCIe link loss. Since
-		 * there is no hardware fix available, prevent the Endpoint
-		 * from advertising L1.2 support by clearing the L1.2 bits in
-		 * the L1 PM Substates Capabilities register. This ensures the
-		 * host will not attempt to enter L1.2 with this Endpoint.
-		 */
-		if (pcie->of_data->disable_l1_2 &&
-		    pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-			val = dw_pcie_readl_dbi(pci, l1ss + PCI_L1SS_CAP);
-			val &= ~(PCI_L1SS_CAP_PCIPM_L1_2 |
-				 PCI_L1SS_CAP_ASPM_L1_2);
-			dw_pcie_writel_dbi(pci, l1ss + PCI_L1SS_CAP, val);
-		}
 	}
 
 	/* Program L0s and L1 entrance latencies */
@@ -1903,6 +1911,7 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
 	config_gen3_gen4_eq_presets(pcie);
 
 	init_host_aspm(pcie);
+	tegra_pcie_disable_ep_l1_2(pcie);
 
 	if (!pcie->of_data->has_l1ss_exit_fix) {
 		val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
-- 
2.34.1