Messages in this thread | | | Subject | Re: [PATCH V13 08/12] dt-bindings: Add PCIe supports-clkreq property | From | Vidya Sagar <> | Date | Wed, 10 Jul 2019 22:44:20 +0530 |
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On 7/10/2019 8:58 PM, Lorenzo Pieralisi wrote: > On Wed, Jul 10, 2019 at 11:52:08AM +0530, Vidya Sagar wrote: >> Some host controllers need to know the existence of clkreq signal routing to >> downstream devices to be able to advertise low power features like ASPM L1 >> substates. Without clkreq signal routing being present, enabling ASPM L1 sub >> states might lead to downstream devices falling off the bus. Hence a new device > > You mean "being disconnected from the bus" right ? I will update it. Yes. I meant the same.
> > Lorenzo > >> tree property 'supports-clkreq' is added to make such host controllers >> aware of clkreq signal routing to downstream devices. >> >> Signed-off-by: Vidya Sagar <vidyas@nvidia.com> >> Reviewed-by: Rob Herring <robh@kernel.org> >> Reviewed-by: Thierry Reding <treding@nvidia.com> >> --- >> V13: >> * None >> >> V12: >> * Rebased on top of linux-next top of the tree >> >> V11: >> * None >> >> V10: >> * None >> >> V9: >> * None >> >> V8: >> * None >> >> V7: >> * None >> >> V6: >> * s/Documentation\/devicetree/dt-bindings/ in the subject >> >> V5: >> * None >> >> V4: >> * Rebased on top of linux-next top of the tree >> >> V3: >> * None >> >> V2: >> * This is a new patch in v2 series >> >> Documentation/devicetree/bindings/pci/pci.txt | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt >> index 2a5d91024059..29bcbd88f457 100644 >> --- a/Documentation/devicetree/bindings/pci/pci.txt >> +++ b/Documentation/devicetree/bindings/pci/pci.txt >> @@ -27,6 +27,11 @@ driver implementation may support the following properties: >> - reset-gpios: >> If present this property specifies PERST# GPIO. Host drivers can parse the >> GPIO and apply fundamental reset to endpoints. >> +- supports-clkreq: >> + If present this property specifies that CLKREQ signal routing exists from >> + root port to downstream device and host bridge drivers can do programming >> + which depends on CLKREQ signal existence. For example, programming root port >> + not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal. >> >> PCI-PCI Bridge properties >> ------------------------- >> -- >> 2.17.1 >>
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