PCI: tegra194: Increase LTSSM poll time on surprise link down

On surprise link down, LTSSM state transits from L0 -> Recovery.RcvrLock ->
Recovery.RcvrSpeed -> Gen1 Recovery.RcvrLock -> Detect. Recovery.RcvrLock
and Recovery.RcvrSpeed transit times are 24 ms and 48 ms respectively, so
the total time from L0 to Detect is ~96 ms. Increase the poll timeout to
120 ms to account for this.

While at it, add LTSSM state defines for Detect-related states and use them
in the poll condition. Use readl_poll_timeout() instead of
readl_poll_timeout_atomic() in tegra_pcie_dw_pme_turnoff() since that path
runs in non-atomic context.

Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://patch.msgid.link/20260324190755.1094879-3-mmaddireddy@nvidia.com

1 files changed, 21 insertions, 15 deletions

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 13949f6f7d5b..94113b2e3308 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -137,7 +137,11 @@
 #define APPL_DEBUG_PM_LINKST_IN_L0		0x11
 #define APPL_DEBUG_LTSSM_STATE_MASK		GENMASK(8, 3)
 #define APPL_DEBUG_LTSSM_STATE_SHIFT		3
-#define LTSSM_STATE_PRE_DETECT			5
+#define LTSSM_STATE_DETECT_QUIET		0x00
+#define LTSSM_STATE_DETECT_ACT			0x08
+#define LTSSM_STATE_PRE_DETECT_QUIET		0x28
+#define LTSSM_STATE_DETECT_WAIT			0x30
+#define LTSSM_STATE_L2_IDLE			0xa8
 
 #define APPL_RADM_STATUS			0xE4
 #define APPL_PM_XMT_TURNOFF_STATE		BIT(0)
@@ -198,7 +202,8 @@
 #define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_MASK	GENMASK(11, 8)
 #define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_SHIFT	8
 
-#define LTSSM_TIMEOUT 50000	/* 50ms */
+#define LTSSM_DELAY_US		10000	/* 10 ms */
+#define LTSSM_TIMEOUT_US	120000	/* 120 ms */
 
 #define GEN3_GEN4_EQ_PRESET_INIT	5
 
@@ -1597,15 +1602,14 @@ static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
 		data &= ~APPL_CTRL_LTSSM_EN;
 		writel(data, pcie->appl_base + APPL_CTRL);
 
-		err = readl_poll_timeout_atomic(pcie->appl_base + APPL_DEBUG,
-						data,
-						((data &
-						APPL_DEBUG_LTSSM_STATE_MASK) >>
-						APPL_DEBUG_LTSSM_STATE_SHIFT) ==
-						LTSSM_STATE_PRE_DETECT,
-						1, LTSSM_TIMEOUT);
+		err = readl_poll_timeout(pcie->appl_base + APPL_DEBUG, data,
+			((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_QUIET) ||
+			((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_ACT) ||
+			((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_PRE_DETECT_QUIET) ||
+			((data & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_WAIT),
+			LTSSM_DELAY_US, LTSSM_TIMEOUT_US);
 		if (err)
-			dev_info(pcie->dev, "Link didn't go to detect state\n");
+			dev_info(pcie->dev, "LTSSM state: 0x%x detect timeout: %d\n", data, err);
 	}
 	/*
 	 * DBI registers may not be accessible after this as PLL-E would be
@@ -1685,12 +1689,14 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
 	appl_writel(pcie, val, APPL_CTRL);
 
 	ret = readl_poll_timeout(pcie->appl_base + APPL_DEBUG, val,
-				 ((val & APPL_DEBUG_LTSSM_STATE_MASK) >>
-				 APPL_DEBUG_LTSSM_STATE_SHIFT) ==
-				 LTSSM_STATE_PRE_DETECT,
-				 1, LTSSM_TIMEOUT);
+		((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_QUIET) ||
+		((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_ACT) ||
+		((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_PRE_DETECT_QUIET) ||
+		((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_DETECT_WAIT) ||
+		((val & APPL_DEBUG_LTSSM_STATE_MASK) == LTSSM_STATE_L2_IDLE),
+		LTSSM_DELAY_US, LTSSM_TIMEOUT_US);
 	if (ret)
-		dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
+		dev_info(pcie->dev, "LTSSM state: 0x%x detect timeout: %d\n", val, ret);
 
 	reset_control_assert(pcie->core_rst);