linux-kernel - [RFC v1 2/2] PCI: tegra: Use readl_poll

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Message-ID: <20250831190055.7952-3-linux.amoon@gmail.com>
Date: Mon,  1 Sep 2025 00:30:51 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Thierry Reding <thierry.reding@...il.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	linux-tegra@...r.kernel.org (open list:PCI DRIVER FOR NVIDIA TEGRA),
	linux-pci@...r.kernel.org (open list:PCI DRIVER FOR NVIDIA TEGRA),
	linux-kernel@...r.kernel.org (open list)
Cc: Anand Moon <linux.amoon@...il.com>
Subject: [RFC v1 2/2] PCI: tegra: Use readl_poll_timeout() for link status polling

Replace the manual `do-while` polling loops with the readl_poll_timeout()
helper when checking the link DL_UP and DL_LINK_ACTIVE status bits
during link bring-up. This simplifies the code by removing the open-coded
timeout logic in favor of the standard, more robust iopoll framework.
The change improves readability and reduces code duplication.

Cc: Thierry Reding <thierry.reding@...il.com>
Signed-off-by: Anand Moon <linux.amoon@...il.com>
---
 drivers/pci/controller/pci-tegra.c | 38 ++++++++++++------------------
 1 file changed, 15 insertions(+), 23 deletions(-)

diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
index 3841489198b64..8e850f7c84e40 100644
--- a/drivers/pci/controller/pci-tegra.c
+++ b/drivers/pci/controller/pci-tegra.c
@@ -24,6 +24,7 @@
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/irq-msi-lib.h>
 #include <linux/irqdomain.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/module.h>
@@ -2157,37 +2158,28 @@ static bool tegra_pcie_port_check_link(struct tegra_pcie_port *port)
 	value |= RP_PRIV_MISC_PRSNT_MAP_EP_PRSNT;
 	writel(value, port->base + RP_PRIV_MISC);
 
-	do {
-		unsigned int timeout = TEGRA_PCIE_LINKUP_TIMEOUT;
-
-		do {
-			value = readl(port->base + RP_VEND_XP);
-
-			if (value & RP_VEND_XP_DL_UP)
-				break;
-
-			usleep_range(1000, 2000);
-		} while (--timeout);
+	while (retries--) {
+		int err;
 
-		if (!timeout) {
+		err = readl_poll_timeout(port->base + RP_VEND_XP, value,
+					 value & RP_VEND_XP_DL_UP,
+					 1000,
+					 TEGRA_PCIE_LINKUP_TIMEOUT * 1000);
+		if (err) {
 			dev_dbg(dev, "link %u down, retrying\n", port->index);
 			goto retry;
 		}
 
-		timeout = TEGRA_PCIE_LINKUP_TIMEOUT;
-
-		do {
-			value = readl(port->base + RP_LINK_CONTROL_STATUS);
-
-			if (value & RP_LINK_CONTROL_STATUS_DL_LINK_ACTIVE)
-				return true;
-
-			usleep_range(1000, 2000);
-		} while (--timeout);
+		err = readl_poll_timeout(port->base + RP_LINK_CONTROL_STATUS,
+					 value,
+					 value & RP_LINK_CONTROL_STATUS_DL_LINK_ACTIVE,
+					 1000, TEGRA_PCIE_LINKUP_TIMEOUT * 1000);
+		if (!err)
+			return true;
 
 retry:
 		tegra_pcie_port_reset(port);
-	} while (--retries);
+	}
 
 	return false;
 }
-- 
2.50.1