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Subject[PATCH] PCI: altera: Poll for link training status after retraining the link
Date
Poll for link training status is cleared before poll for link up status.
This can help to get the reliable link up status, especially when PCIe
is in Gen 3 speed.

Signed-off-by: Ley Foon Tan <lftan@altera.com>
---
drivers/pci/host/pcie-altera.c | 45 ++++++++++++++++++++++++++++++++++--------
1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/host/pcie-altera.c b/drivers/pci/host/pcie-altera.c
index 2b78376..58eef99 100644
--- a/drivers/pci/host/pcie-altera.c
+++ b/drivers/pci/host/pcie-altera.c
@@ -61,7 +61,8 @@
#define TLP_LOOP 500
#define RP_DEVFN 0

-#define LINK_UP_TIMEOUT 5000
+#define LINK_UP_TIMEOUT HZ
+#define LINK_RETRAIN_TIMEOUT HZ

#define INTX_NUM 4

@@ -99,11 +100,44 @@ static bool altera_pcie_link_is_up(struct altera_pcie *pcie)
return !!((cra_readl(pcie, RP_LTSSM) & RP_LTSSM_MASK) == LTSSM_L0);
}

+static void altera_wait_link_retrain(struct pci_dev *dev)
+{
+ u16 reg16;
+ unsigned long start_jiffies;
+ struct altera_pcie *pcie = dev->bus->sysdata;
+
+ /* Wait for link training end. */
+ start_jiffies = jiffies;
+ for (;;) {
+ pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &reg16);
+ if (!(reg16 & PCI_EXP_LNKSTA_LT))
+ break;
+
+ if (time_after(jiffies, start_jiffies + LINK_RETRAIN_TIMEOUT)) {
+ dev_err(&pcie->pdev->dev, "link retrain timeout\n");
+ break;
+ }
+ udelay(100);
+ }
+
+ /* Wait for link is up */
+ start_jiffies = jiffies;
+ for (;;) {
+ if (altera_pcie_link_is_up(pcie))
+ break;
+
+ if (time_after(jiffies, start_jiffies + LINK_UP_TIMEOUT)) {
+ dev_err(&pcie->pdev->dev, "link up timeout\n");
+ break;
+ }
+ udelay(100);
+ }
+}
+
static void altera_pcie_retrain(struct pci_dev *dev)
{
u16 linkcap, linkstat;
struct altera_pcie *pcie = dev->bus->sysdata;
- int timeout = 0;

if (!altera_pcie_link_is_up(pcie))
return;
@@ -121,12 +155,7 @@ static void altera_pcie_retrain(struct pci_dev *dev)
if ((linkstat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB) {
pcie_capability_set_word(dev, PCI_EXP_LNKCTL,
PCI_EXP_LNKCTL_RL);
- while (!altera_pcie_link_is_up(pcie)) {
- timeout++;
- if (timeout > LINK_UP_TIMEOUT)
- break;
- udelay(5);
- }
+ altera_wait_link_retrain(dev);
}
}
DECLARE_PCI_FIXUP_EARLY(0x1172, PCI_ANY_ID, altera_pcie_retrain);
--
1.8.2.1
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