On Mon, 19 Feb 2018 17:14:06 -0600, Bjorn Helgaas said: > Change "pcie_port_pm=force" to enable power management of conventional PCI > bridges and hotplug bridges as well as PCIe ports. As with the previous > PCIe port-only behavior, this is not expected to work in all systems. This part says the behavior changes - which is itself a Bad Idea unless you have a deprecation cut-over across several releases. The general rule is that you're not allowed to break somebody's kernel without a lot of warning. Remember that there's probably a lot of embedded systems that hardcode their boot cmdline and changing the behavior can result in a failed boot - which can be a royal bitch to debug if the embedded system doesn't have a console..... In addition, it doesn't match the actual patch, which documents the boot parameter as being removed, rather than the behavior changed: > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 1d1d53f85ddd..4660105ec851 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -3143,10 +3147,6 @@ > compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe > ports driver. > > - pcie_port_pm= [PCIE] PCIe port power management handling: > - off Disable power management of all PCIe ports > - force Forcibly enable power management of all PCIe ports > - And *that* doesn't match the rest of the patch, which never touches the handling of that parameter, either changing it or removing it.
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