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| author | Bjorn Helgaas <bhelgaas@google.com> | 2020-12-15 15:11:10 -0600 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2020-12-15 15:11:10 -0600 |
| commit | 7546ad5e3c20d93e15ad38916a7661846e9c247d (patch) | |
| tree | 5cb86a13c257299df8084c79e1b876416d568aae /drivers | |
| parent | 7c250f8293a362189419ae8b34da111ba02af304 (diff) | |
| parent | 1d1cd163d0de22a4041a6f1aeabcf78f80076539 (diff) | |
Merge branch 'remotes/lorenzo/pci/aardvark'
- Update comment about delay before link training (Pali Rohár)
* remotes/lorenzo/pci/aardvark:
PCI: aardvark: Update comment about disabling link training
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/pci/controller/pci-aardvark.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 1043e54c73bd..051b48bd7985 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -252,7 +252,14 @@ static void advk_pcie_issue_perst(struct advk_pcie *pcie) if (!pcie->reset_gpio) return; - /* PERST does not work for some cards when link training is enabled */ + /* + * As required by PCI Express spec (PCI Express Base Specification, REV. + * 4.0 PCI Express, February 19 2014, 6.6.1 Conventional Reset) a delay + * for at least 100ms after de-asserting PERST# signal is needed before + * link training is enabled. So ensure that link training is disabled + * prior de-asserting PERST# signal to fulfill that PCI Express spec + * requirement. + */ reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG); reg &= ~LINK_TRAINING_EN; advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG); |