diff options
| -rw-r--r-- | src/device/pciexp_device.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/src/device/pciexp_device.c b/src/device/pciexp_device.c index 0c3653879b..bc8206a6d4 100644 --- a/src/device/pciexp_device.c +++ b/src/device/pciexp_device.c @@ -50,16 +50,34 @@ unsigned int pciexp_find_extended_cap(device_t dev, unsigned int cap) #define PCIE_TRAIN_RETRY 10000 static int pciexp_retrain_link(device_t dev, unsigned cap) { - unsigned try = PCIE_TRAIN_RETRY; + unsigned int try; u16 lnk; + /* + * Implementation note (page 633) in PCIe Specification 3.0 suggests + * polling the Link Training bit in the Link Status register until the + * value returned is 0 before setting the Retrain Link bit to 1. + * This is meant to avoid a race condition when using the + * Retrain Link mechanism. + */ + for (try = PCIE_TRAIN_RETRY; try > 0; try--) { + lnk = pci_read_config16(dev, cap + PCI_EXP_LNKSTA); + if (!(lnk & PCI_EXP_LNKSTA_LT)) + break; + udelay(100); + } + if (try == 0) { + printk(BIOS_ERR, "%s: Link Retrain timeout\n", dev_path(dev)); + return -1; + } + /* Start link retraining */ lnk = pci_read_config16(dev, cap + PCI_EXP_LNKCTL); lnk |= PCI_EXP_LNKCTL_RL; pci_write_config16(dev, cap + PCI_EXP_LNKCTL, lnk); /* Wait for training to complete */ - while (try--) { + for (try = PCIE_TRAIN_RETRY; try > 0; try--) { lnk = pci_read_config16(dev, cap + PCI_EXP_LNKSTA); if (!(lnk & PCI_EXP_LNKSTA_LT)) return 0; |