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| author | Pali Rohár <pali@kernel.org> | 2021-11-24 23:49:22 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-08 08:46:51 +0100 |
| commit | 14910c1f4ff475031bb4114a399d742074340f04 (patch) | |
| tree | 9085a3a723d2267a3f43fa5d802584f35446a6c6 /drivers | |
| parent | 7e81c76e62410f707363215ce1695ce0c92dfa6a (diff) | |
| download | linux-stable-14910c1f4ff475031bb4114a399d742074340f04.tar.gz linux-stable-14910c1f4ff475031bb4114a399d742074340f04.tar.bz2 linux-stable-14910c1f4ff475031bb4114a399d742074340f04.zip | |
PCI: aardvark: Update comment about disabling link training
commit 1d1cd163d0de22a4041a6f1aeabcf78f80076539 upstream.
According to PCI Express Base Specifications (rev 4.0, 6.6.1
"Conventional reset"), after fundamental reset a 100ms delay is needed
prior to enabling link training.
Update comment in code to reflect this requirement.
Link: https://lore.kernel.org/r/20201202184659.3795-1-pali@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/pci/host/pci-aardvark.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/pci/host/pci-aardvark.c b/drivers/pci/host/pci-aardvark.c index 68ab3aef0e12..66c4b9282420 100644 --- a/drivers/pci/host/pci-aardvark.c +++ b/drivers/pci/host/pci-aardvark.c @@ -275,7 +275,14 @@ 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); |