Messages in this thread | | | From | Andy Shevchenko <> | Date | Fri, 1 Jun 2018 18:12:24 +0300 | Subject | Re: [PATCH v2] PCI: Check for PCIe downtraining conditions |
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On Fri, Jun 1, 2018 at 6:01 PM, Alexandru Gagniuc <mr.nuke.me@gmail.com> wrote: > PCIe downtraining happens when both the device and PCIe port are > capable of a larger bus width or higher speed than negotiated. > Downtraining might be indicative of other problems in the system, and > identifying this from userspace is neither intuitive, nor straigh > forward. > > The easiest way to detect this is with pcie_print_link_status(), > since the bottleneck is usually the link that is downtrained. It's not > a perfect solution, but it works extremely well in most cases.
> +static void pcie_check_upstream_link(struct pci_dev *dev) > +{
> +
This is redundant, but...
> + if (!pci_is_pcie(dev)) > + return; > + > + /* Look from the device up to avoid downstream ports with no devices. */ > + if ((pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT) && > + (pci_pcie_type(dev) != PCI_EXP_TYPE_LEG_END) && > + (pci_pcie_type(dev) != PCI_EXP_TYPE_UPSTREAM)) > + return;
...wouldn't be better
int type = pci_pcie_type(dev);
?
But also possible, looking at existing code,
static inline bool pci_is_pcie_type(dev, type) { return pci_is_pcie(dev) ? pci_pcie_type(dev) == type : false; }
-- With Best Regards, Andy Shevchenko
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