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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
This commit is contained in:
Bjorn Helgaas 2020-12-15 15:11:10 -06:00
parent 7c250f8293 1d1cd163d0
commit 7546ad5e3c
1 changed files with 8 additions and 1 deletions
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9
drivers/pci/controller/pci-aardvark.c
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@ -252,7 +252,14 @@ static void advk_pcie_issue_perst(struct advk_pcie *pcie)
if (!pcie->reset_gpio) if (!pcie->reset_gpio)
return; 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 = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
reg &= ~LINK_TRAINING_EN; reg &= ~LINK_TRAINING_EN;
advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG); advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);