[PATCH v9 08/14] PCI: Use distinct local vars in `pcie_retrain_link'

Maciej W. Rozycki
2023-06-11T17:20:34Z

Use separate local variables to hold the respective values retrieved
from the Link Control Register and the Link Status Register. Not only
it improves readability, but it makes it possible for the compiler to
detect actual uninitialised use should this code change in the future.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
---
New change in v9.
---
drivers/pci/pci.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

linux-pcie-retrain-link-lnkctl-lnksta.diff
Index: linux-macro/drivers/pci/pci.c
===================================================================
--- linux-macro.orig/drivers/pci/pci.c
+++ linux-macro/drivers/pci/pci.c
@@ -4922,30 +4922,31 @@ bool pcie_wait_for_link(struct pci_dev *
bool pcie_retrain_link(struct pci_dev *pdev)
{
unsigned long end_jiffies;
- u16 reg16;
+ u16 lnkctl;
+ u16 lnksta;

- pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &reg16);
- reg16 |= PCI_EXP_LNKCTL_RL;
- pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, reg16);
+ pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &lnkctl);
+ lnkctl |= PCI_EXP_LNKCTL_RL;
+ pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnkctl);
if (pdev->clear_retrain_link) {
/*
* Due to an erratum in some devices the Retrain Link bit
* needs to be cleared again manually to allow the link
* training to succeed.
*/
- reg16 &= ~PCI_EXP_LNKCTL_RL;
- pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, reg16);
+ lnkctl &= ~PCI_EXP_LNKCTL_RL;
+ 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, &reg16);
- if (!(reg16 & PCI_EXP_LNKSTA_LT))
+ 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 !(reg16 & PCI_EXP_LNKSTA_LT);
+ return !(lnksta & PCI_EXP_LNKSTA_LT);
}

/*