linux-kernel - [PATCH v9 09/14] PCI: Factor our waiting for link training end

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Date:   Sun, 11 Jun 2023 18:19:49 +0100 (BST)
From:   "Maciej W. Rozycki" <macro@...am.me.uk>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
cc:     Alex Williamson <alex.williamson@...hat.com>,
        Lukas Wunner <lukas@...ner.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Stefan Roese <sr@...x.de>, Jim Wilson <wilson@...iptree.org>,
        David Abdurachmanov <david.abdurachmanov@...il.com>,
        Pali Rohár <pali@...nel.org>,
        linux-pci@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v9 09/14] PCI: Factor our waiting for link training end

Move code polling for the Link Training bit to clear into a function of 
its own.

Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
---
New change in v9.
---
 drivers/pci/pci.c |   37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

linux-pcie-wait-for-link-status.diff
Index: linux-macro/drivers/pci/pci.c
===================================================================
--- linux-macro.orig/drivers/pci/pci.c
+++ linux-macro/drivers/pci/pci.c
@@ -4850,6 +4850,28 @@ static int pci_pm_reset(struct pci_dev *
 }
 
 /**
+ * pcie_wait_for_link_status - Wait for link training end
+ * @pdev: Device whose link to wait for.
+ *
+ * Return TRUE if successful, or FALSE if training has not completed
+ * within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds.
+ */
+static bool pcie_wait_for_link_status(struct pci_dev *pdev)
+{
+	unsigned long end_jiffies;
+	u16 lnksta;
+
+	end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS);
+	do {
+		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta);
+		if (!(lnksta & PCI_EXP_LNKSTA_LT))
+			break;
+		msleep(1);
+	} while (time_before(jiffies, end_jiffies));
+	return !(lnksta & PCI_EXP_LNKSTA_LT);
+}
+
+/**
  * pcie_wait_for_link_delay - Wait until link is active or inactive
  * @pdev: Bridge device
  * @active: waiting for active or inactive?
@@ -4916,14 +4938,11 @@ bool pcie_wait_for_link(struct pci_dev *
  * pcie_retrain_link - Request a link retrain and wait for it to complete
  * @pdev: Device whose link to retrain.
  *
- * Return TRUE if successful, or FALSE if training has not completed
- * within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds.
+ * Return TRUE if successful, or FALSE if training has not completed.
  */
 bool pcie_retrain_link(struct pci_dev *pdev)
 {
-	unsigned long end_jiffies;
 	u16 lnkctl;
-	u16 lnksta;
 
 	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &lnkctl);
 	lnkctl |= PCI_EXP_LNKCTL_RL;
@@ -4938,15 +4957,7 @@ bool pcie_retrain_link(struct pci_dev *p
 		pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnkctl);
 	}
 
-	/* Wait for link training end. Break out after waiting for timeout. */
-	end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS);
-	do {
-		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta);
-		if (!(lnksta & PCI_EXP_LNKSTA_LT))
-			break;
-		msleep(1);
-	} while (time_before(jiffies, end_jiffies));
-	return !(lnksta & PCI_EXP_LNKSTA_LT);
+	return pcie_wait_for_link_status(pdev);
 }
 
 /*