| Message ID | 20190710062212.1745-9-vidyas@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI: tegra: Add Tegra194 PCIe support | expand |
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. 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 >
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 >>
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 -------------------------