On Tue, Mar 9, 2021 at 12:31 AM Nadeem Athani <nadeem@xxxxxxxxxxx> wrote: > > The parameter detect-quiet-min-delay can be used to program the minimum > time that LTSSM waits on entering Detect.Quiet state. > 00 : 0us minimum wait time in Detect.Quiet state. > 01 : 100us minimum wait time in Detect.Quiet state. > 10 : 1000us minimum wait time in Detect.Quiet state. > 11 : 2000us minimum wait time in Detect.Quiet state. What determines this setting? Is it per board or SoC? Is this a standard PCI timing thing? Why does this need to be tuned per platform? > Signed-off-by: Nadeem Athani <nadeem@xxxxxxxxxxx> > --- > .../devicetree/bindings/pci/cdns,cdns-pcie-host.yaml | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml > index 293b8ec318bc..a1d56e0be419 100644 > --- a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml > +++ b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml > @@ -27,6 +27,18 @@ properties: > > msi-parent: true > > + detect-quiet-min-delay: > + description: > + LTSSM Detect.Quiet state minimum delay. > + 00 : 0us minimum wait time > + 01 : 100us minimum wait time > + 10 : 1000us minimum wait time > + 11 : 2000us minimum wait time > + $ref: /schemas/types.yaml#/definitions/uint32 > + minimum: 0 > + maximum: 3 > + default: 0 > + > required: > - reg > - reg-names > @@ -48,6 +60,7 @@ examples: > linux,pci-domain = <0>; > vendor-id = <0x17cd>; > device-id = <0x0200>; > + detect-quiet-min-delay = <0>; > > reg = <0x0 0xfb000000 0x0 0x01000000>, > <0x0 0x41000000 0x0 0x00001000>; > -- > 2.15.0 >
