linux-kernel - [PATCH V4 03/22] PCI: tegra194: Fix polling delay for L2 state

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Message-ID: <20260126074519.3426742-4-mmaddireddy@nvidia.com>
Date: Mon, 26 Jan 2026 13:15:00 +0530
From: Manikanta Maddireddy <mmaddireddy@...dia.com>
To: <bhelgaas@...gle.com>, <lpieralisi@...nel.org>, <kwilczynski@...nel.org>,
	<mani@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
	<conor+dt@...nel.org>, <thierry.reding@...il.com>, <jonathanh@...dia.com>,
	<jingoohan1@...il.com>, <vidyas@...dia.com>, <cassel@...nel.org>,
	<18255117159@....com>
CC: <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Manikanta
 Maddireddy" <mmaddireddy@...dia.com>
Subject: [PATCH V4 03/22] PCI: tegra194: Fix polling delay for L2 state

From: Vidya Sagar <vidyas@...dia.com>

As per PCIe spec r6.0, sec 5.3.3.2.1, after sending PME_Turn_Off message,
Root port should wait for 1~10 msec for PME_TO_Ack message. Currently,
driver is polling for 10 msec with 1 usec delay which is aggressive.
Change it to 10 msec polling with 100 usec delay. Since this function
is used in non-atomic context only, use non-atomic poll function.

Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")

Signed-off-by: Vidya Sagar <vidyas@...dia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@...dia.com>
---
V4:
* None

V3:
* Changed atomic call to non-atomic call
* Reworded the commit message

V2:
* None

 drivers/pci/controller/dwc/pcie-tegra194.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index ab2c3f07ed4f..0b8c1a7ca232 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -199,7 +199,8 @@
 #define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_MASK	GENMASK(11, 8)
 #define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_SHIFT	8
 
-#define PME_ACK_TIMEOUT 10000
+#define PME_ACK_DELAY		100   /* 100 us */
+#define PME_ACK_TIMEOUT		10000 /* 10 ms */
 
 #define LTSSM_TIMEOUT 50000	/* 50ms */
 
@@ -1555,9 +1556,9 @@ static int tegra_pcie_try_link_l2(struct tegra_pcie_dw *pcie)
 	val |= APPL_PM_XMT_TURNOFF_STATE;
 	appl_writel(pcie, val, APPL_RADM_STATUS);
 
-	return readl_poll_timeout_atomic(pcie->appl_base + APPL_DEBUG, val,
-				 val & APPL_DEBUG_PM_LINKST_IN_L2_LAT,
-				 1, PME_ACK_TIMEOUT);
+	return readl_poll_timeout(pcie->appl_base + APPL_DEBUG, val,
+				  val & APPL_DEBUG_PM_LINKST_IN_L2_LAT,
+				  PME_ACK_DELAY, PME_ACK_TIMEOUT);
 }
 
 static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
-- 
2.34.1