+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4656,6 +4656,7 @@
norid [S390] ignore the RID field and force use of
one PCI domain per PCI function
notph [PCIE] Do not use PCIe TPH
+ nostmode [PCIE] Force TPH to use No ST Mode
Needs a little more context here about what this means. Users won't
know where to even look for "No ST Mode" unless they have a copy of
the spec.