[V13,08/12] dt-bindings: Add PCIe supports-clkreq property
diff mbox series

Message ID 20190710062212.1745-9-vidyas@nvidia.com
State New
Headers show
Series
  • PCI: tegra: Add Tegra194 PCIe support
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Commit Message

Vidya Sagar July 10, 2019, 6:22 a.m. UTC
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
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(+)

Comments

Lorenzo Pieralisi July 10, 2019, 3:28 p.m. UTC | #1
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
>
Vidya Sagar July 10, 2019, 5:14 p.m. UTC | #2
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
>>

Patch
diff mbox series

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
 -------------------------