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

Maciej W. Rozycki
2023-06-11T17:21:02Z

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

Signed-off-by: Maciej W. Rozycki <macro@orcam.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);
}

/*