[PATCH 05/11] PCI: tegra194: Check for 16 GT/s capability before programming

[Manikanta Maddireddy <mmaddireddy@nvidia.com>]

config_gen3_gen4_eq_presets() added PCI_PL_16GT_LE_CTRL to the result of
dw_pcie_find_ext_capability() without checking whether the 16 GT/s
capability exists. If the capability is absent, the code writes lane
presets at an unrelated configuration offset.

Look up the capability once before the lane loop and skip the 16 GT/s lane
equivalent control programming when it is absent.

Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index aa47052a37cf..358156c63da0 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -840,7 +840,11 @@ static void tegra_pcie_enable_interrupts(struct dw_pcie_rp *pp)
 static void config_gen3_gen4_eq_presets(struct tegra_pcie_dw *pcie)
 {
 	struct dw_pcie *pci = &pcie->pci;
-	u32 val, offset, i;
+	u32 pl16g, val, i;
+
+	pl16g = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_PL_16GT);
+	if (pl16g)
+		pl16g += PCI_PL_16GT_LE_CTRL;
 
 	/* Program init preset */
 	for (i = 0; i < pcie->num_lanes; i++) {
@@ -851,15 +855,15 @@ static void config_gen3_gen4_eq_presets(struct tegra_pcie_dw *pcie)
 			     GEN3_GEN4_EQ_PRESET_INIT);
 		dw_pcie_writew_dbi(pci, CAP_SPCIE_CAP_OFF + (i * 2), val);
 
-		offset = dw_pcie_find_ext_capability(pci,
-						     PCI_EXT_CAP_ID_PL_16GT) +
-				PCI_PL_16GT_LE_CTRL;
-		val = dw_pcie_readb_dbi(pci, offset + i);
+		if (!pl16g)
+			continue;
+
+		val = dw_pcie_readb_dbi(pci, pl16g + i);
 		FIELD_MODIFY(PCI_PL_16GT_LE_CTRL_DSP_TX_PRESET_MASK, &val,
 			     GEN3_GEN4_EQ_PRESET_INIT);
 		FIELD_MODIFY(PCI_PL_16GT_LE_CTRL_USP_TX_PRESET_MASK, &val,
 			     GEN3_GEN4_EQ_PRESET_INIT);
-		dw_pcie_writeb_dbi(pci, offset + i, val);
+		dw_pcie_writeb_dbi(pci, pl16g + i, val);
 	}
 
 	val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
-- 
2.34.1